PC: (Although some are also on consoles)
Dungeon Defenders (Tower Defence type RPG game)
Saints Row 3 (I had a blast in coop)
Little Big Planet 1+2
Portal 2
Worms (Reloaded is pretty good)
Dead Island
Left 4 Dead 1+2
System Shock 2 (Although its not easy to find and probably need some tuning to get coop working)
League of Legends (A DotA-like game and its free too)
Theres also countless Half-Life 2 mods worth looking at (I'd warmly recommend Zombie Master)
PS3:
Sports Championship (PSMove game)
Earth Defence Force: Insect Armageddon (Which is also on steam now)
Tumble (PSMove game)
All I got atm, unless i go boot up the PS3.. oh and of course Monster Hunter: Freedom Unite, but that needs 2 PSP's
Dungeon Defenders (Tower Defence type RPG game)
Saints Row 3 (I had a blast in coop)
Little Big Planet 1+2
Portal 2
Worms (Reloaded is pretty good)
Dead Island
Left 4 Dead 1+2
System Shock 2 (Although its not easy to find and probably need some tuning to get coop working)
League of Legends (A DotA-like game and its free too)
Theres also countless Half-Life 2 mods worth looking at (I'd warmly recommend Zombie Master)
PS3:
Sports Championship (PSMove game)
Earth Defence Force: Insect Armageddon (Which is also on steam now)
Tumble (PSMove game)
All I got atm, unless i go boot up the PS3.. oh and of course Monster Hunter: Freedom Unite, but that needs 2 PSP's