And just based on what I've read/heard in the last few days:
David Cutcliffe - Duke
Sonny Dykes - La Tech
Most assume these two will be top targets because of ties to UK or Barnhart. I've cast my lot in with Dykes. He seems to be the top target from all accounts. Neal Brown's name at Tech has also come up in conjunction with Dykes as a potential OC if Tubbs is headed to another SEC school like Arkansas.
Dirk Koetter - Former Arizona State, Current Falcons OC
I read earlier that he's shown interest in the position. I have no idea why (don't know who his connections are or anything like that). I don't know if he's just not happy in Atlanta or what.
Phil Fulmer - Former Tennessee HC
Ron Zook - Former Illinois and Florida HC
These two have also come up in several places, but generally together with Fulmer as HC and Zook as DC. I would kill for Zook as a DC.