Damn most I would mention have already been. The Tales of games have a co- op element to the combat. It's pretty damn cool from the very kitty I've experienced with friends.
PSN has the PixelJunk games, Shooter 1&2 and Eden I know for sure, that have co-op.
Then you got Castle Crashers, Scott Pilgrim vs The World, Double a Dragon Neon for beat me ups. I know there are more as looking these up will usually yield others under a "Related Titles" type of banner.
There's Hardcore Uprising as an anime-styled remake of Contra by Arc Systems Works - the guys behind BlazBlue, Guilty Gear, P4: Arena, Arcana Hearts 3, and Chaos Code.
And to get more fringe I hear Kane & Lynch 1(not 2 as that is a middle finger to games in general) is pretty good for its co-op in its uniqueness for the players seeing different things as Kane or Lynch. Army of Two I hear is decent but again not its sequels.
I'm sure I know more they just are t coming to me right now. --- http://backloggery.com/ryuvega NP- LoZ:ALBW, Borderlands 2, RaC:ItN 'I've seen Ryu on the MtG board so he's already cooler than most of you.' ~ XImperialDragon
I wouldn't recommend playing co-op with the Tales games. Yes, there is co-op during combat but everything else is single player which can be really boring for the other person. That's the reason my wife and I stopped playing Tales of Graces F together.