As a programmer I do need a lot of icons. And since I am cheap bastard, I usually try to get free ones.
Company from which I got most freebie offers is definitely IconShock. Guys just can't stop producing free icon sets. Latest is their Social icon set. It has image for any social site there is (both raster and vector). And best of all - these icons are FREE for COMMERCIAL use also.
Yes, they may not earn much money that way, but they will always have my eternal love for this. Who knows, maybe I will even stop being cheap and buy something from them finally.
In any case I do love these guys.
P.S. They do not sponsor me. This is spontaneous outburst of pure love.