Some other good multiplayer games:

Rodland: Cute platformer.
Parasol Stars: One of my favourite platform games ever. It was hard to master, but managed to complete it in the end. Have played this a lot in two-player mode.
Deluxe Galaga: Oh yeah, this shoot'em up simply rocked!

I also remember the other games mentioned here, like Sensible Soccer, Kick Off, Speedball 2, Skidmarks and so on. All great games!