I'm making a list of game-ready model shops, if you know another ones please tell me ^^ here's what I've found so far:
(alphabetically sorted)

3dbud.com

(fantasy characters - animals - monters) -
http://3dbud.com

3drt.com

(fantasy - scifi characters - animals - monters)
http://3drt.com

adenfall.com

(game objects)
http://adenfall.com

arteria-gaming.com

(game objects)
http://arteria-gaming.com

cubixstudio.com

(fantasy - scifi characters)
http://cubixstudio.com

dexsoft-games.com

(game objects - fantasy - scifi characters)
http://dexsoft-games.com

frogames.net

(game objects - fantasy - scifi characters)
http://frogames.net

gamebeep.com

(game objects - fantasy - scifi characters)
http://gamebeep.com

game-stuff.com

(game objects - game levels)
http://game-stuff.com

Don't forget daz3d.com and its forums.