From Abel as the Punisher to Zangief as Colossus, with a little Guile as Duke Nukem thrown in, you can find them over at Fileplanet. If someone's got a cool skin but you haven't unlocked the character, they show you how.
Most importantly, for you non-modders, they promise screenshots will be uploaded sometime later today. What are you waiting for? Get going over there and hit F5 for the rest of the afternoon. Street Fighter 4 Super Skin Combo Attack [Fileblog via VE3D]