In 2006, I attended the science fiction/fantasy/comic book convention Dragon*Con, along with 30,000 of my closest friends.
It was a blast.
D*C really is vastly ginormously huge, with an expected attendance this year of 40,000. Yes, 4x104 fans. The guest list is already awesome, even this early: Adam Baldwin (JAYNE! from FIREFLY!), James Randi, James Hong (Lo Pan from Big Trouble in Little China, the best movie ever made, ever), and lots more to come. Pamela Gay and Fraser Cain will be there too, and there's a whole thread on skepticism.
Hawesome. Totally and completely. So if you're in Atlanta at the end of August, you should go. But get tickets now! They go fast, and the hotels (four of them) are probably already booked. Yes, it's that ginormous.