Major League Gaming got 25 invitations from Microsoft that give early access to the Halo Wars demo, and is holding a drawing to see who gets 'em. Winners can play it a week early.
The demo goes out Feb. 5; these codes will get you in on Jan. 29. MLG's asking entrants to just post in a thread on one of their forums and the winners will be chosen at random. Of course, that requires you to register an account there, so you can see where MLG is going with this.