I could see Halo Trilogy coming to Steam. They been looking at
Steam as a option.Plus, the game's old and PC gamers been asking for it, for years - and the X360's pretty much on its last legs in its console cycle.
Personally, I'd also love to see Gears of War 2 + 3 and especially Fable 2 finally come to the PC, as well.
I'm wondering how well some of their Microsoft-published Indie titles on Steam (Mark of the Ninja, Deadlight) and Fable 3 sold on Steam; especially during the Steam Winter Sale.
Microsoft has been publishing a few more titles on Steam lately. Recently, Microsoft has their 5-Game Indie Bundle on Amazon DVG (that requires Steam) - and I'm betting it sold well on Amazon DVG; especially during that EC Coupon Sale.