Just hazarding a guess here, but my foreskin radar is surprisingly reliable:
All cut except:
Benicio Del Toro
Jason Statham
Orlando Bloom
and possibly
Vin Diesel
I tend to concurr except for Vin Diesel where I have ambiguious foreskindar info.
In "The Talented Mr Ripley", if you freeze frame the scene when Mat Damon put on the yellow swimming suit, you can see on a few frames a fairly obvious shape of a circumcised penis.
I use to see some chance Aflek was uncut. But now, I think the odds of that are fairly low.
My foreskindar had also targetted Ryan Reynolds (of 2 guys a girl and pizza place or Van Wilder fame) as possibly uncut. But There are a few pics of him on the net where he is naked and if you look carefully, it appear to be cut. (one of them is picture from behind and you can sort of see the glans on the side of scrotum.
Hayden Christensen (Anakin Skywalker/Darth Vader) is likely uncut. Northern european parents giving this vancouver born a european name, and he looks uncut too.
By default, all young british born actors are uncut, with a couple of exceptions.
John Leguizamo is uncut.
One tidbit that interests me are reports that Sean Connery is uncut (no surprise) but that his son (Jason Connery) would be cut. Would be an interesting to get more facts on this.
One major foreskindar question is John Corbett (the radio DJ in Northern Exposure and one of the boyfriends of Carrie in Sex and the City). I have no hard info on him, but my foreskindar says "uncut". On a late night show, he was once asked what his most profound Northern Exposure episode was, and his reply was the one where Holling decides to get circumcised and he said that it was one topic that was highly personal. Only an uncut growing up in the USA would think about that issue. (Holling feels his foreskin will be a turn off to his girlfriend and wants to get the snip).