This Visual Studio Extension searches for unused images in your web project (and optionally removes them)
Download it from the "release" section.
OR - get it here http://visualstudiogallery.msdn.microsoft.com/fb7a9b9c-08e1-4bb4-91b4-8e512feb5a1b
OR - find it in the VS extensions gallery right within visual studio. Just type "unused image" into the search box.
Right-click your project in solution explorer and choose "Find unused images"
First, it scans a project for image files, then it searches for references in .aspx/.ashx/.cs/.css/.js/.cshtml and other files.
MIT license. AKA "do whatever you want, just make sure you link to the author"
© developed by (& heavily used at) Jitbit™ the company behind Jitbit Helpdesk