What Are Some Good Team Based Fps/tps Games for Ps3/pc?

What are some good TPS/FPS (FPS preferred) games for PS3/PC? I mean a game where you actually have to help your team mates. DO NOT say Call of Duty, Battlefield or MGS. I have them all and the only good one is MGS but it broke.

Thanks in advance.

Suggestion:

Team Fortress 2 is very team based FPS game. Certain game modes force you to play cooperatively if you intend to win. Also its just tons of fun, been playing it for 3 years almost, really great game. Also id like to note, please do buy it on the PC if you can, the PC version of TF2 has tons of exclusive content such as maps and weapons and more that are not available to the console versions. Plus all the content is free and there is more to come for it in the future. Besides i do recall hearing that the TF2 community for the PS3 is almost nonexistent whereas on the PC its thriving even up to now, there are several thousands of players online.

Could not agree with you more on CoD, team work is nonexistent in that series, just mindless shooting and running.