Flaticon - A database of free vector icons.
Game-Icons - Huge collection of free icons for games and apps.
Iconfinder - Iconfinder is the leading search engine and market place for vector icons in SVG, PNG, CSH and AI format..
IconArchive - Search through more than 735,000 free icons. Browse icons by category, artist, popularity, date. Organize and share your favorites.
HDwallpapers.net - HDwallpapers.
The Noun Project - Creating, Sharing and Celebrating the World's Visual Language