Preorder L4D2, get 10% off and a beret for Team Fortress 2
Valve's running a preorder incentive on the PC version of Left 4 Dead 2, where you not only get 10 percent off the cost of the game, but Bill's beret from Left 4 Dead 1 for your Team Fortress 2 character.
If you already preordered the game, Valve said to fire-up your TF2 game and the beret will be ready and waiting for you.
Check with your local retailer to make sure it's participating, though, just to be sure.
Full thing's over on the TF2 blog.