My 3 picks other than Tiger (watch out, he looks to be really close and you know he hates it that he hasn't won a major in nearly 2 years) are:
Singh - Just like you can count on the sun coming up everyday, you can count on Singh being there.
Campbell - I think that you will see him contend in many US Opens in the future.
Garcia - Dude is pretty hot these days, I am still not sure if he is mature enough though. He seems to be hitting it REAL good.
There really aren't alot of Americans playing that great right now, Singh, Els, and Garcia have been running things since the Masters.
I would love to see Lefty win but I think that it is more likely for him to miss the cut, has he played well since the Masters? I don't think that he has.
I see Tiger winning on Sunday though, sorry to go so far out on a limb there.