IconStore - Free icon packs by first-class designers
silhoutteAC - More than 47,000 vector silhouettes for free
Feather Icons - Simply beautiful open source icons
IconBros - Free and continuously growing high quality icons
Iconjar - Store all your icons in one place, just a click away
MakeAppIcon - MakeAppIcon resizes and optimizes your icon designs into all formats needed for iOS and Android mobile app!