I did a search to see if anyone had posted this and didnt find one. CA is an online FPS with very impressive maps, weapons, and it's with other players online. The matches are set up into two teams with game sets of capture the flag, elimination, and others. This isn't an in depth approach like America's Army (which I couldnt get into). While it does have a ranking system in which you gain experience by playing, the set up is impressively quick. The best aspect about it is it's free. It would be cool to get a TFP clan going.
Combat Arms - Online FPS Action