wow this thread is very useful. Thanks for going this in depth haha. I'm going to print out the list before I go tommorow and we'll honestly have time to at least try out most of the games on the list.

more from NES

Battle Tank
Ikari Warriors II: Victory Road
Ikari Warriors III: The Rescue
Legendary Wings
NArc
Silkworm
Smash TV
Snow Bros

Genesis games
Vapor Trail, basically a raiden clone, but a good one, plus one of the few co-op shooters on the genesis
Double Dragon, Very close to the arcade original but with a much much more stable frame rate.
Arcus Odyssey- 2 player action rpg
Forgotten Worlds- port of the arcade game, has a really strange glitch that causes the game to give you game over if you are using 6 button controllers, or have an emulator set as such

Snes,
Run-saber, basically a co-op strider
Pocky and Rocky 1 & 2, 2 player action rpg
Mr.Do!, arcade classic with an added co-op mode
Kirby's Dreamland 3

I think I updated everything listed so far. Let me know if I missed anything, and feel free to keep adding. Good night fuckers.

thought this deserved a bump as the list is a great idea

ps3

marvel ultimate alliance

its multiplat so if its listed for the 360 it might also apply to the ps3, ps2 and psp versions (ps3 and 360 versions are identical)

Sport games are included?

there needs to be an arcade list:
x-men
the simpsons game
alien vs predator
TMNT: turtles in time (also snes but even better for arcade)
smash tv
total carnage

saturn:
guardian heroes
dungeons and dragons (import only i believe)

dreamcast:
cannon spike
power stone 2 (co-op story and team battes)
nfl blitz: 2001
gauntlet legends

ps2:
gauntlet: dark legacy
the adventures of cookie and cream

---- i kinda feel that SMG galaxy should be taken off the list. it is really a one player game to the core with a haphazard two people mode.

Super Bomberman 1, 2, 3, 4, 5 on the SNES they were all brilliant for co-op matches :)

You forgot Kane and Lynch for the 360 and PS3, oh and Army of 2, great list btw.