diff --git a/src/main/scala/app/AccountController.scala b/src/main/scala/app/AccountController.scala
index 17fca02..1997363 100644
--- a/src/main/scala/app/AccountController.scala
+++ b/src/main/scala/app/AccountController.scala
@@ -58,10 +58,10 @@
     getAccountByUserName(userName).flatMap(_.image).map { image =>
       contentType = FileUtil.getMimeType(image)
       new java.io.File(getUserUploadDir(userName), image)
-    } getOrElse {
-      contentType = "image/png"
-      Thread.currentThread.getContextClassLoader.getResourceAsStream("noimage.png")
-    }
+//    } getOrElse {
+//      contentType = "image/png"
+//      Thread.currentThread.getContextClassLoader.getResourceAsStream("noimage.png")
+    } getOrElse NotFound
   }
 
   get("/:userName/_edit")(oneselfOnly {
diff --git a/src/main/scala/app/ControllerBase.scala b/src/main/scala/app/ControllerBase.scala
index a22d6cc..7d88da8 100644
--- a/src/main/scala/app/ControllerBase.scala
+++ b/src/main/scala/app/ControllerBase.scala
@@ -10,6 +10,7 @@
 import model.Account
 import scala.Some
 import service.AccountService
+import javax.servlet.http.HttpServletRequest
 
 /**
  * Provides generic features for controller implementations.
@@ -22,7 +23,7 @@
   /**
    * Returns the context object for the request.
    */
-  implicit def context: Context = Context(servletContext.getContextPath, LoginAccount, currentURL)
+  implicit def context: Context = Context(servletContext.getContextPath, LoginAccount, currentURL, request)
 
   private def currentURL: String = {
     val queryString = request.getQueryString
@@ -94,7 +95,7 @@
 /**
  * Context object for the current request.
  */
-case class Context(path: String, loginAccount: Option[Account], currentUrl: String)
+case class Context(path: String, loginAccount: Option[Account], currentUrl: String, request: HttpServletRequest)
 
 /**
  * Base trait for controllers which manages account information.
diff --git a/src/main/scala/util/StringUtil.scala b/src/main/scala/util/StringUtil.scala
index bd42fb9..bc478c7 100644
--- a/src/main/scala/util/StringUtil.scala
+++ b/src/main/scala/util/StringUtil.scala
@@ -8,4 +8,10 @@
     md.digest.map(b => "%02x".format(b)).mkString
   }
 
+  def md5(value: String): String = {
+    val md = java.security.MessageDigest.getInstance("MD5")
+    md.update(value.getBytes)
+    md.digest.map(b => "%02x".format(b)).mkString
+  }
+
 }
diff --git a/src/main/scala/view/helpers.scala b/src/main/scala/view/helpers.scala
index db2d804..fdb3734 100644
--- a/src/main/scala/view/helpers.scala
+++ b/src/main/scala/view/helpers.scala
@@ -2,6 +2,8 @@
 import java.util.Date
 import java.text.SimpleDateFormat
 import twirl.api.Html
+import util.StringUtil
+import service.AccountService
 
 /**
  * Provides helper methods for Twirl templates.
@@ -74,6 +76,29 @@
       .replaceAll("(^|\\W)([a-f0-9]{40})(\\W|$)", "$1<a href=\"%s/%s/%s/commit/$2\">$2</a>$3").format(context.path, repository.owner, repository.name))
 
   /**
+   * Returns &lt;img&gt; which displays the avatar icon.
+   * Looks up Gravatar if avatar icon has not been configured in user settings.
+   */
+  def avatar(userName: String, size: Int, tooltip: Boolean = false)(implicit context: app.Context): Html = {
+    val account = Option(context.request.getAttribute("cache.account." + userName).asInstanceOf[model.Account]).orElse {
+      new AccountService {}.getAccountByUserName(userName).map { account =>
+        context.request.setAttribute("cache.account." + userName, account)
+        account
+      }
+    }
+    val src = account.collect { case account if(account.image.isEmpty) =>
+      s"""http://www.gravatar.com/avatar/${StringUtil.md5(account.mailAddress)}?s=${size}"""
+    } getOrElse {
+      s"""${context.path}/${userName}/_avatar"""
+    }
+    if(tooltip){
+      Html(s"""<img src=${src} class="avatar" style="width: ${size}px; height: ${size}:px" data-toggle="tooltip" title=${userName}/>""")
+    } else {
+      Html(s"""<img src=${src} class="avatar" style="width: ${size}px; height: ${size}:px" />""")
+    }
+  }
+
+  /**
    * Implicit conversion to add mkHtml() to Seq[Html].
    */
   implicit def extendsHtmlSeq(seq: Seq[Html]) = new {
diff --git a/src/main/twirl/account/activity.scala.html b/src/main/twirl/account/activity.scala.html
index da65fcc..29b2982 100644
--- a/src/main/twirl/account/activity.scala.html
+++ b/src/main/twirl/account/activity.scala.html
@@ -6,7 +6,7 @@
     <div class="row-fluid">
       <div class="span4">
         <div class="block">
-          <div class="account-image">@helper.html.avatar(account.userName, 200)</div>
+          <div class="account-image">@avatar(account.userName, 200)</div>
           <div class="block-header">@account.userName</div>
         </div>
         <div class="block">
diff --git a/src/main/twirl/account/repositories.scala.html b/src/main/twirl/account/repositories.scala.html
index dbdacf5..9a2ce34 100644
--- a/src/main/twirl/account/repositories.scala.html
+++ b/src/main/twirl/account/repositories.scala.html
@@ -6,7 +6,7 @@
     <div class="row-fluid">
       <div class="span4">
         <div class="block">
-          <div class="account-image">@helper.html.avatar(account.userName, 200)</div>
+          <div class="account-image">@avatar(account.userName, 200)</div>
           <div class="block-header">@account.userName</div>
         </div>
         <div class="block">
diff --git a/src/main/twirl/admin/users/list.scala.html b/src/main/twirl/admin/users/list.scala.html
index 1fef459..abe96f4 100644
--- a/src/main/twirl/admin/users/list.scala.html
+++ b/src/main/twirl/admin/users/list.scala.html
@@ -14,7 +14,7 @@
               <a href="@path/admin/users/@account.userName/_edit">Edit</a>
             </div>
             <div class="strong">
-              @helper.html.avatar(account.userName, 20)
+              @avatar(account.userName, 20)
               <a href="@url(account.userName)">@account.userName</a>
               @if(account.isAdmin){
                 (Administrator)
diff --git a/src/main/twirl/helper/activities.scala.html b/src/main/twirl/helper/activities.scala.html
index 7cac4de..93519b4 100644
--- a/src/main/twirl/helper/activities.scala.html
+++ b/src/main/twirl/helper/activities.scala.html
@@ -8,7 +8,7 @@
     <div class="block">
       <div class="muted small">@datetime(activity.activityDate)</div>
       <div class="strong">
-        @helper.html.avatar(activity.activityUserName, 16)
+        @avatar(activity.activityUserName, 16)
         @activityMessage(activity.message)
       </div>
       @activity.additionalInfo.map { additionalInfo =>
diff --git a/src/main/twirl/helper/avatar.scala.html b/src/main/twirl/helper/avatar.scala.html
deleted file mode 100644
index 4612f3e..0000000
--- a/src/main/twirl/helper/avatar.scala.html
+++ /dev/null
@@ -1,8 +0,0 @@
-@(userName: String, size: Int, tooltip: Boolean = false)(implicit context: app.Context)
-@import context._
-@import view.helpers._
-@if(tooltip){
-  <img src="@url(userName)/_avatar" data-toggle="tooltip" title="@userName" class="avatar" style="width: @(size)px; height: @(size)px;"/>
-} else {
-  <img src="@url(userName)/_avatar" class="avatar" style="width: @(size)px; height: @(size)px;"/>
-}
diff --git a/src/main/twirl/helper/uploadavatar.scala.html b/src/main/twirl/helper/uploadavatar.scala.html
index a008cfb..59a4993 100644
--- a/src/main/twirl/helper/uploadavatar.scala.html
+++ b/src/main/twirl/helper/uploadavatar.scala.html
@@ -4,7 +4,9 @@
   @if(account.nonEmpty && account.get.image.nonEmpty){
     <img src="@path/@account.get.userName/_avatar" style="with: 120px; height: 120px;"/>
   } else {
-    <div id="clickable">No Image</div>
+    <div id="clickable">
+      <a href="https://www.gravatar.com/" target="_blank">Gravatar</a> is used
+    </div>
   }
 </div>
 @if(account.nonEmpty && account.get.image.nonEmpty){
diff --git a/src/main/twirl/issues/create.scala.html b/src/main/twirl/issues/create.scala.html
index 54bdcfc..cfa330a 100644
--- a/src/main/twirl/issues/create.scala.html
+++ b/src/main/twirl/issues/create.scala.html
@@ -23,7 +23,7 @@
                 <li><a href="javascript:void(0);" class="assign" data-name=""><i class="icon-remove-circle"></i> Clear assignee</a></li>
                 <li class="divider"></li>
                 @collaborators.map { collaborator =>
-                  <li><a href="javascript:void(0);" class="assign" data-name="@collaborator"><i class="icon-while"></i>@helper.html.avatar(collaborator, 20) @collaborator</a></li>
+                  <li><a href="javascript:void(0);" class="assign" data-name="@collaborator"><i class="icon-while"></i>@avatar(collaborator, 20) @collaborator</a></li>
                 }
               }
             }
diff --git a/src/main/twirl/issues/issue.scala.html b/src/main/twirl/issues/issue.scala.html
index ae65e40..218c721 100644
--- a/src/main/twirl/issues/issue.scala.html
+++ b/src/main/twirl/issues/issue.scala.html
@@ -31,7 +31,7 @@
           <div class="issue-info">
             <span id="label-assigned">
               @issue.assignedUserName.map { userName =>
-                @helper.html.avatar(userName, 20) <a href="@url(userName)" class="username strong">@userName</a> is assigned
+                @avatar(userName, 20) <a href="@url(userName)" class="username strong">@userName</a> is assigned
               }.getOrElse("No one is assigned")
             </span>
             @if(hasWritePermission){
@@ -39,7 +39,7 @@
                 <li><a href="javascript:void(0);" class="assign" data-name=""><i class="icon-remove-circle"></i> Clear assignee</a></li>
                 <li class="divider"></li>
                 @collaborators.map { collaborator =>
-                  <li><a href="javascript:void(0);" class="assign" data-name="@collaborator"><i class="icon-white"></i>@helper.html.avatar(collaborator, 20) @collaborator</a></li>
+                  <li><a href="javascript:void(0);" class="assign" data-name="@collaborator"><i class="icon-white"></i>@avatar(collaborator, 20) @collaborator</a></li>
                 }
               }
             }
diff --git a/src/main/twirl/issues/list.scala.html b/src/main/twirl/issues/list.scala.html
index 1aa62f6..3fa59f2 100644
--- a/src/main/twirl/issues/list.scala.html
+++ b/src/main/twirl/issues/list.scala.html
@@ -219,7 +219,7 @@
               }
               <span class="pull-right muted">
                 @issue.assignedUserName.map { userName =>
-                  @helper.html.avatar(userName, 20, true)
+                  @avatar(userName, 20, true)
                 }
                 #@issue.issueId
               </span>
diff --git a/src/main/twirl/repo/commit.scala.html b/src/main/twirl/repo/commit.scala.html
index 2ac2af5..60a872b 100644
--- a/src/main/twirl/repo/commit.scala.html
+++ b/src/main/twirl/repo/commit.scala.html
@@ -43,7 +43,7 @@
     </tr>
     <tr>
       <td>
-        @helper.html.avatar(commit.committer, 20)
+        @avatar(commit.committer, 20)
         <a href="@url(commit.committer)" class="username strong">@commit.committer</a>
         <span class="muted">@datetime(commit.time)</span>
         <div class="pull-right monospace small" style="text-align: right;">
diff --git a/src/main/twirl/repo/commits.scala.html b/src/main/twirl/repo/commits.scala.html
index 469d0bb..0a6e6aa 100644
--- a/src/main/twirl/repo/commits.scala.html
+++ b/src/main/twirl/repo/commits.scala.html
@@ -38,7 +38,7 @@
             <a href="@url(repository)/tree/@commit.id" class="small">Browse code</a>
           </div>
           <div>
-            <div class="commit-avatar-image">@helper.html.avatar(commit.committer, 40)</div>
+            <div class="commit-avatar-image">@avatar(commit.committer, 40)</div>
             <a href="@url(repository)/commit/@commit.id" class="commit-message" style="font-weight: bold;">@link(commit.summary, repository)</a>
             @if(commit.description.isDefined){
               <a href="javascript:void(0)" onclick="$('#description-@commit.id').toggle();" class="omit">...</a>
diff --git a/src/main/twirl/repo/files.scala.html b/src/main/twirl/repo/files.scala.html
index 60acfed..1cb2434 100644
--- a/src/main/twirl/repo/files.scala.html
+++ b/src/main/twirl/repo/files.scala.html
@@ -36,7 +36,7 @@
       <tr>
         <td colspan="4" class="latest-commit">
           <div>
-            @helper.html.avatar(latestCommit.committer, 20)
+            @avatar(latestCommit.committer, 20)
             <a href="@url(latestCommit.committer)" class="username strong">@latestCommit.committer</a>
             <span class="muted">@datetime(latestCommit.time)</span>
             <div class="pull-right align-right monospace">
diff --git a/src/main/twirl/wiki/history.scala.html b/src/main/twirl/wiki/history.scala.html
index 859f0f8..d40a0c0 100644
--- a/src/main/twirl/wiki/history.scala.html
+++ b/src/main/twirl/wiki/history.scala.html
@@ -35,7 +35,7 @@
     @commits.map { commit =>
       <tr>
         <td width="0%"><input type="checkbox" name="commitId" value="@commit.id"></td>
-        <td>@helper.html.avatar(commit.committer, 20)<a href="@url(commit.committer)">@commit.committer</a></td>
+        <td>@avatar(commit.committer, 20)<a href="@url(commit.committer)">@commit.committer</a></td>
         <td width="80%">
           <span class="muted">@datetime(commit.time):</span>
           @commit.shortMessage