Freeiconsdownload.com as self-explanatory as it’s name, has a massive archive of free icons you will find handy for your GUI or web design. Whether you are looking for icons for applications, cartoons, computers,people, sports, etc, freeiconsdownload have somethingin their categories.

“More than 500.000 stock icons for web and software; Vista, MAC, XP and original design styles… most of them including vector sources (illustrator)… icons for all kind of business (general, accounting,networking, medical, etc)”