Now I only play on instantchess,
Instantchess
On chessclub there are GM's and IM's and other master players playing. But don't make yourself any illusions, if you are not yourself one, they won't play you anyway.
(I myself am a non-master average amateur player)
chessclub

Some other sites of interest

A vast collection of games:
chessgames
News from the chess world:
chassbase