What are your go-to couch co-op games?

A friend and I have been jamming through co-op biz on the PS2 and having a great time. Timesplitters 2 and 3, LotR: Return of the King, Obscure, and Darkwatch are what we've played so far.

What else would you fine folks recommend, and what did you enjoy yourself? Pretty much down to play any genre. I did like Balfour's Gate: DA back in the day and heard Champions of Norrath was worth a shot, too?