I believe there's a repticon show July 26-27. I plan on going, getting B-Day gift for myself, as it's a few days after my birthday. http://www.repticon.com/atlanta/
I think there's usually a show in put on by GA herptelogical center, it's going to be October 25-26, 2008. I went to one last year, but most of the vendors had snakes, turtles, spiders, etc. Very few leopard geckos and crested geckos. http://www.georgiaherpetologicalsociety.org/expo.html
You just missed the one in March. I'm not sure if there are goign to be any others. Google reptile show (or expo) in georgia. Usually you can find one in Birmingham,AL ever 2 weeks or so, but I've heard it isn't too great of a show. http://www.dixiereptileshow.com/
I try to keep an updated calender of shows, but I've sense given up as the dates change so often.