graphicPUSH: Free icons and free icon sets for web designers.
Free! Icons for your website or application at MaxPower
AJAX Activity indicators | Animated GIFs designed to indicate your site is doing something
A collection of royalty-free animated GIF icons to use when your web application is loading
famfamfam.com: Icons
famfamfam is the personal website of Mark James
Telegraphics - Free Plugins for Photoshop
Free Photoshop and Illustrator plugins, and other software, including GPL source code