I really like the work the Designer's Republic did on the Wipeout games
also I really like the stuff i've seen done by Jon Burgerman and Paris Hair. 123Klan has an interesting site too
bluespeed9 has gorgeous 3D work as does Trecman (who also does 2D stuff).
Their website are these:
http://www.thedesignersrepublic.com/
http://www.jonburgerman.com/
http://www.parishair.com/
http://www.123klan.com/
http://bluespeed9.deviantart.com/
http://trecman.deviantart.com/
Enjoy the links