3 player co-op

[KiloFox]

it's not exactly co-op... but Dragon's Dogma lets you use the Main Pawns of 2 other people... so if you play it, and so do 2 of your friends on the same console, then you can play with their pawns, which gives bonuses too...

 

[chozo_hybrid]

Transformers: War for Cybertron has a three player co-op campaign.

 

[blazearmoru]

Dungeon Land.

 

[sabercrusader]

LOTR: War in the North
Uncharted 2 & 3.
That's about it that comes to mind.

 

[Crrato]

PixelJunk Eden. One of my favorite PSN games. Also on Steam.