Most fun simultaneous co-op games?

I wanna hear other's suggestions as I have played the crap out of the games I already have. Please no games past the 64-Bit time period, as this is a classic game section of the forum and I am only looking to accept games from then or before (preferably before).

GAMES I ALREADY PLAY

Battletoads (NES)
Contra (NES)
Gunstar Heroes (Genesis)
Streets of Rage (Genesis)
Golden Axe (Genesis)
Legendary Wings (NES)
Firepower 2000 (SNES)
Ms. Pac-Man (Genesis)