Not that UGA is looking for a new DC, but hypothetically, if they were, TCU's Dick Bumpas is one of the best defensive coordinators in the country. A finalist for the Broyles Award, he has the 2nd ranked defense in 2008 and had the 2nd ranked defense in 2006 in the scoring happy Mountain West Conference with Utah and BYU.
If you want a shiny new DC, this wouldn't be a bad place to look. Read more about Bumpas here and here. One little nugget that would make you smile... in 1996, as Navy's DC, the middies beat Ga. Tech at the Joke. Unfortunately, I think PJ was the OC for that Navy team.
Bumpas is not a newbie and he sure as hell knows what he is doing. There is some speculation that TCU HC Gary Patterson is the brains behind the TCU defense, but I am not sure. Bumpas was his mentor before Patterson became a HC. I don't know much about Bumpas personally - whether he would fit in with Coach Richt's staff, etc - but he has put some great defenses on the field in his career.