http://www.telerik.com/demos/aspnet/prometheus/ComboBox/Examples/Default/DefaultCS.aspx
... shown below, and it does not work. Error it gives is "imagepath is not a valid attribute of element radcomboboxitems.
<telerik:RadComboBox
ID="RadComboBox_Broker" runat="server"
Width="200px" Height="115px"
Skin="Vista"
MarkFirstMatch="false" HighlightTemplatedItems="True"
ShowToggleImage="True" AllowCustomText="false" EnableLoadOnDemand="false">
<ItemTemplate>
<div class="qsfexBrokerView">
<img class="qsfexBrokerPic" src='Images/people/<%# DataBinder.Eval(Container, "Attributes['ImagePath']") %>' alt="" />
<span class="qsfexBrokerName"><%# DataBinder.Eval(Container, "Text") %></span>
</div>
</ItemTemplate>
<Items>
<telerik:RadComboBoxItem
ImagePath="images/black.gif"
Text="Florence Osbourne">
</telerik:RadComboBoxItem>
<telerik:RadComboBoxItem
ImagePath="pic2.jpg"
Text="Ildó Zinnia">
</telerik:RadComboBoxItem>
<telerik:RadComboBoxItem
ImagePath="pic3.jpg"
Text="Josephine Steph">
</telerik:RadComboBoxItem>
<telerik:RadComboBoxItem
ImagePath="pic4.jpg"
Text="Abe Rodney">
</telerik:RadComboBoxItem>
</Items>
</telerik:RadComboBox>