Free Icons
Icons are great for web-design, gui-design, and a host of other things like making the desktop of your dream. However, professional icons can be rather expensive. Instead of forking over money for icons there are two really good resources for getting them for free.
The first is at interfaceLift they provide free icons which look really slick. These icons are mainly used for making your applications look better in your dock or have better shortcuts on your desktop.
The other site is Iconfinder.net here they provide a “web 2.0″ interface in searching for icons. This site is extremely useful in putting together prototypes and user interface mockups.
If you have found any other sites with great free icons add the link in the comment section.