This anecdotal report suggests that Dean might have the same reservations I do regarding him chairing the DNC:

There was a Q&A at the end of the session, and somebody asked about the DNC.  Interestingly, Dean made it obvious that he still had reservations.  First  of all, he said that he was committed to DFA regardless. Secondly, he said he was still considering a 2008 presidential run, which the DNC Chairmanship would preclude.  But then, he started talking about the difficulties of reforming institutions from the inside, and how he wasn't sure he really wanted to do that.  He acknowledged it would take longer from an external vantage point, but he seemed to have real concerns about his ability and even desire to chair the DNC.

Kos has been suggesting Simon Rosenberg of NDN as another possibility (see also this diary from Stirling Newberry for more on why Rosenberg - Newberry usually irritates me, but is occasionally trenchant.)

Here is the list of 400 who vote on the DNC chair and here is more about Rosenberg's group.