The only stab I'd take is Shiller just because his name has been near the top of the list of potentials for years now and that sort of says something. That would be well deserved. Project Syndicate mentions Rogoff who would also be a great choice. The nice thing about both of these guys is that they are reasonably well known outside of their field of expertise. Rogoff has gotten a lot of press lately for his work with Reinhart on sovereign debt, and Shiller is in the news and also has (relatively) general reading type books.
But they both have also made important contributions to economics, in financial economics and open economy macro, respectively.
Nordhaus, Barro, Thaler, Hansen, Ross, Atkinson, and Deaton are all mentioned in this WSJ post. I have no opinion on most of them. Barro certainly has a lifetime of contributions, although I think some are problematic. Nordhaus would certainly kick up some interesting discussions.
My view on who deserves it? I think we really need some subset (or all of them) of a Card/Angrist/Krueger prize for non-experimental econometrics and labor market analysis. I don't think that's an implausible one at all, and every year it strikes me more that they oughta have one.
I suggested Pissarides/Mortenson on the eve of their prize and got it right (which was pretty awesome because I didn't even see anyone else suggest them at the time), so we'll see if my Card/Angrist/Krueger suggestion works out too.
The other guy I've always figured is in the cards eventually is John Taylor. That would also generate an interesting discussion since everyone is so ready to kick thinking in terms of interest rates out of central banking.