I see a few prime candidates:
1. Richard Thaler joint with Robert Schiller.
2. Martin Weitzman and William Nordhaus, for their work on environmental economics.
3. Three prominent econometricians of your choice, bundled.
4. Jean Tirole, possibly bundled with Oliver Hart and other game theorists/principle agent theorists. But last year the prize was in a similar field so the chances here have gone down for the time being.
5. Doug Diamond, bundled with another theorist or two of financial intermediation, such as John Geanakopolos. Bernanke probably has to wait, although that may militate against the entire idea of such a prize right now.
6. Dale Jorgenson plus ???? (Baumol?) for a productivity prize.
I see #1 or #2 as most likely, with Al Roth and Ernst Fehr also in the running. Sadly, it seems it is too late for the deserving Tullock.
In general I think Robert Barro has a good chance but I don't see him being picked so close to a financial crisis; the pick would be seen as an endorsement of Barro's negative attitude toward fiscal stimulus and I don't expect that from the Swedes. The financial crisis is a problem for Fama especially, though he is arguably the most deserving of the non-recipients. Paul Romer is another likely winner, although they may wait until rates of growth pick up in the Western world. He is still young. The Thomson-Reuters picks seem too young and for Alesina the political timing probably is not right for the same reasons as Barro.
Here is a blog post on the betting odds for the literature prize; NgŠ©gÄ© wa Thiong'o is rising on the list. Not long ago the absolute favorite was Tomas Tranströmer, who perhaps should start his own line of toys or have his name put on a school of engineering.