Wolfenstein: Enemy territory is an online FPS from Splash Damage and Activision. Originally created as an expansion pack to Return to Castle Wolfenstein, the project was abandoned in an incomplete state, but the multiplayer component was quite playable, so it was released as a freely downloadable standalone multiplayer game. Gameplay is objective-based, and heavily reliant on teamplay.
The developer's website isn't particularly interesting, and there doesn't seem to be an "official" site that hosts the game (there used to be, but it's now dedicated to Quake Wars).
But here are links, for those who are interested:
Splash Damage:
http://www.splashdamage.com/
Former official W:ET website:
http://www.enemyterritory.com/
Quasi-official W:ET website (it's unofficial, but looks official):
http://www.planetwolfenstein.com/enemyterritory/
The first google hit for "wolfenstein enemy territory download":
http://www.3dgamers.com/games/wolfensteinet/
