The Noun Project - Creating, Sharing and Celebrating the World's Visual Language
Flaticon - A database of free vector icons.
HDwallpapers.net - HDwallpapers.
IconPharm - IconPharm is a library of open source icons with recoloring and resizing tools.
Game-Icons - Huge collection of free icons for games and apps.
IconArchive - Search through more than 735,000 free icons. Browse icons by category, artist, popularity, date. Organize and share your favorites.