Swing State Project has an open thread where you can list the top 15 most vulnerable GOP seats next cycle. Without fail, the number one slot is held by Rep.-elect Joseph Cao (R-LA), who managed to overcome the odds in one of the deepest blue districts in the country to oust corrupt incumbent William Jefferson (D).
I have to say, I feel a little bad. Cao seems like a nice enough guy, and he certainly did us a favor by kicking Jefferson to the curb. But alas, there is no way he survives the next cycle. He's the Republican version of Nick Lampson, only in a worse position (the district is even more liberal than Lampson's was conservative, and Lampson had far more political experience than Cao does).
Oh well. Hopefully the Democrats will nominate someone worth supporting to ease the guilt.