THQ and OnLive did it with Homefront, and now they're doing it again with Red Faction: Armageddon. By pre-ordering the game, you'll get a free OnLive Game System that's fully compatible with the streaming service. Additionally, they will help get your ass to mars by throwing in a copy of Red Faction: Guerrilla.
The landing page for this admittedly rather intriguing promotion can be found here. If you're worried about when Armageddon is going to unlock on OnLive, worry not: it's a day-and-date affair, with the specific time set at 12:10 EDT on June 7.
What did you think of the demo, by the way?