Free Icons resources
Free Icons 
Free Icons Web lets you browse and download more than 15,000 free icons for every major desktop operating system on the market. The icons are arranged into galleries and come in different themes and sizes. If you want to show off your talents, you can submit your own icons to the site for others to enjoy.
Icon Archive
The Icon Archive collects more than 20,000 quality icons into convenient categories. These icons are the work of more than 170 artists and can be used on all major desktop operating systems. Whatever your inclinations, you're bound to find a set of icons that suits your tastes.
IconBazaar
Icon Bazaar is home to a large collection of fun icons for all your desktop needs. There are the usual still icons, along with animated icons that will bring your otherwise banal computer desktop to sparkling life. Check out the fractal icons!
Icons4free
Icons 4 Free has icons for free -- no surprises there! Icons come in packs that contain up to 1,000 icons each. At the time of writing, there were a total of 15 packs containing more than 3,500 icons. The site is constantly being updated, so be sure to bookmark it for all your future icon indulgences.
Website Icons
This site has on offer a variety of icons tailored toward the heavy-duty computer user. All icons are clean and crisp, and they're arranged into several categories so you can zero in on the perfect icon for your particular needs. As an added extra, there's a world-flag collection containing the national flag of every country in the world -- a great way to express your patriotic side.