I've posted about this at RedsZone, but I thought it would be fun to bring it up here as the community doesn't completely overlap.
Phil Birnbaum is willing to bet any reasonable sum of real money that you cannot pick a player, set of players, etc, that will improve more in the clutch than any other player, set of players, etc. Bets must be made prior to '08, and will be about 2008 performances.
So, if you think that Edwin Encarnacion is a clutch god and Dunn is worthless in the clutch (and you get to define how "clutch" will be determined--RISP, pLI, close&late, whatever), Phil will take that bet.
If you just want to bet that Dunn will be awful in the clutch, Phil will take that bet too. For example, you can single Dunn out and pit the change in his performance in the clutch against how the rest of the league's performance changes the same clutch situations.
I hope someone takes him up on it, as it'd be a blast to follow over the course of the season.