If you don't have the money to shell out for new multiplayer first-person shooter Brink, don't worry, there are plenty of opportunities to get your multiplayer FPS fix for free! Here are my current favorite free first person shooters:

Quake Live

Quake is so fast paced I would almost classify it as sport! It's a sci-fi shooter, and it's easy to get into but difficult to master. Luckily there are great tutorials, and you won't be pitted against highly skilled players straight away. Quake is an excellent FPS, and a great introduction to the genre too.

Battlefield Heroes

Of the two free Battlefield games, this is the one I prefer. It's fast, fun to play, and really well balanced.  With a good selection of soldier classes and easy to operate vehicles, it's hard not to be charmed by Battlefield Heroes. It's not at all serious, with lots of fun customization to add to the cartoon action.

Battlefield Play4Free

This is a much more hardcore offering. Classic Battlefield maps, and authentic modern warfare are the order of the day. Like Heroes, there are good soldier classes and vehicles, and it's fast paced. Play4Free is much more grown up, but it still offers tight, action packed gaming.

Operation 7

This one is a bit more serious, again.  There's plenty of blood in this FPS, and newbies can expect to be shot. A lot. Get the hang of Operation 7, though, and you'll soon be taking out those newbies yourself!

Combat Arms

With 26 maps, and a ton of customization available, Combat Arms has gained quite  a following. There's nothing sophisticated about the action, but it's good fun. With clans to join and create, plus tons of optional upgrades, there really is a lots to do! Although early versions were glitchy and buggy, that doesn't seem to be a problem anymore.

America's Army 3

Using the Unreal 3 engine, America's Army has come a long way since it's first release. Being the official game of the US military, as you might expect this is a pretty serious game. There is no respawning, meaning once you're dead you have to sit out the game. This actually makes the gameplay pretty tense, and the emphasis on realism is quite refreshing. It's got great tutorials, and I've never seen a game with an option to actually join the army for real before!

NOVA

Are you on Facebook? Then why not gather some friends together and shoot each other? This is another sci-fi shooter, similar to Quake that you can play in your browser, right from Facebook. It's pretty simplistic, but the social aspect makes it an interesting prospect.