I think this list is kinda good, since you can sort the games by of- and online:
http://www.co-optimus.com/system/2/playstation-3.html
But this generation there aren´t really that many games you can play split-screen-4-player that are really worth it, especially co-op! For example I would have loved to play BlackOps-Zombies in 4 player split screen but that wasn`t available...