Free is always good, and it's especially good when the thing you get for free is something you'd want anyway. To promote an upcoming update to Team Fortress 2, Valve announced (via their official site) that they're making the shooter free for everyone all this week. So, for those few people who don't already own the game, you can get in a few matches both before and after the update.
Their site also teases an upcoming "Meet the Medic" video to coincide with the update's Thursday launch, another in the long list of fun "Meet the..." videos. If you missed them before, you owe it to yourself to check out the entries for the Sniper, Soldier, Demo Man, and Heavy.
In between bouts of TF2, you can check back at the official Valve blog for daily updates on what Thursday will bring, but so far they've revealed new weapons for the Spy and the Heavy, as well as a new Payload map called Barnblitz.