Here's a freak scenario for you:
Jimmy Clausen somehow falls to No. 23, which isn't unheard of (see Aaron Rodgers 2005). The Buffalo Bills come calling with a trade offer. Their second round pick (No. 41) and a third round pick (No. 72) for our 23rd overall pick. Knowing that Ted Thompson is a coveter of draft picks, this is quite possible.
In a recent Packers article, the Packers were said to be keeping a "very close" eye on Jonathan Dwyer at the Georgia Tech Pro Day. If he is available at the No. 41 pick received from the Bills, Thompson might not pass on him.
Dwyer is a bruising back at 6'1'' 235 pounds, but has decent speed for his size. He ran a 4.59 40 at the combine and he has the ability to break the long run.
Could that be the reason Ted had a close eye on Dwyer? Maybe he sees him filling the roll played by Ahman Green to give the Packers a reliable back in case Ryan Grant goes down.
Dwyer will be a little behind considering he ran the fullback position for the Georgia Tech Yellow Jackets, who are one of few teams that run the triple option in Division I college football. He has the ability to make the switch in the NFL. He will need to get adjusted to catching the ball out of the back field considering he didn't do that at Tech.
I think there is zero chance Thompson takes a RB in the first round (unless C.J. Spiller absolutely plummets). I think there is even less of a chance that Clausen falls and we trade down to get this pick where I have Dwyer selected.
However, weirder things have happened in the draft.