Here are quotes from some relevant candidates from The Hill's survey of 97 senators on whether they'd agree to be VP:

Sen. Evan Bayh (D-Ind.) "It's presumptuous to even speculate about that kind of thing. But I suspect that's not the sort of thing you say no to."

Sen. Joseph Biden (D-Del.)
"I'm happy being called 'Mr. Chairman.' "

Sen. Chuck Hagel (R-Neb.)
"I'm not here to talk about that."

Sen. Kay Bailey Hutchison (R-Texas)
"I just really don't have any comment beyond what I've said about that, that I don't want to go in that direction at all."

Sen. John Kerry (D-Mass.)
"I don't get into hypotheticals. No, I haven't considered it. I don't have a clue, honestly."

Sen. Joe Lieberman (I-Conn.)
"Once is enough. I already have the T-shirt and I'm proud of it. I yield to my colleagues."

Sen. Claire McCaskill (D-Mo.)
"If I were asked, I would ask some mental health professionals to visit Barack Obama. I just think Sen. Obama is way too smart to pick me. I'm not a good pick, and he's smarter than that. That's why he's going to make such a good president."

Sen. Jim Webb (D-Va.)
"I'm not really interested. That's all I want to say."

I said the "relevant" ones, but check out the rest, especially from those senators that don't have a shot. Some good stuff.