There are a bunch of guys with a shot at this year's US Open. Tiger and Phil will be on the first 2 pages of the leaderboard. One of them may win though I just don't see Tiger winning after being off of competetive golf for such a long time with limited practice. He's light years better than everyone else but these guys should be good enough to hold him off this year.
Sergio, Phil, Immelman, and Scott are probably the top group to look at.
As for outsiders or "dark(er) horses" I look at Driving Accuracy, Total Driving, and Greens hit in regulation. Boo Weekley, Robert Allenby, Hunter Mahan, Stewart Cink, Rod Pampling, Jim Furyk, Justin Leonard - all of these guys are way up there in those categories. I think the later two don't have 7600 yards in them but Justin's hot right now so we'll see.
My pic is Sergio. A bit of a "sexy" pic but he's hitting the ball well and he's had a pretty solid last 4-5 weeks. If his putter hangs in there for him he can give it a run. Something interesting I heard on Peter Kessler's XM radio show this morning. Sergio is #1 on tour in 3-putt avoidance. That is very surprising considering his highly publicized woes on the green. So he's just not making some of those birdie putts. If he can stay patient, play fairways and greens he'll stay out of his way and give himself a shot.