I don't have too many. I thought Red Faction was kinda cool, but really short and not very well developed multiplayer. I think Timesplitters 2 is fun, just because of the massive number of characters to choose from.
I thought both of the first 007 games were horrible, but I've never played the new one (and don't plan to, with my dislike for the first two).
Never really liked Medal of Honor, simply because I couldn't get past the first level. I bought it at a yard sale, tried playing it a few times, and never could beat that first level. I couldn't see anything, thanks to the shakiness of the screen and the sand exploding around me. That and the fact that I kept getting killed in the most cheap ways devised by man...
I guess SOCOM is more of a 3rd person shooter, and I was never good enough at that game to play online.
My favorite FPS (finally getting to the point after all that rambling) is definately Tribes: Aerial Assault. I like this game much more than I'll ever like Halo. My bro and I used to play Tribes online all the time, and always would be the best players in the match. I disliked the inability to chat properly with my teammates, but the gameplay more than made up for it. If you ever get the chance, make sure to at least rent this game (worthwhile only online or a botmatch. The singleplayer campaign isn't all that great).