The VeryIcom.com is a icon search engine, it contents over 20000 high quaility web icons in more than 1000 icon packs. Each Icon has serval file formats such as PNG, ICO, you can free browse and download for Windows, Macintosh and Linux Systems.
All the icons can be free used for non-commercial, but part of them copyright belongs original author, if you want to use icons for commercial purposes, you have to pay for obtain the author's License agreement.
If you are an icon designer and you want to share your artworks to others, please send a mail to firstname.lastname@example.org or submit you artworks on http://www.veryicon.com/submit.php. High quality Free Icons artist is welcome.