Returned tickets just went onsale for Comic-Con International, and have probably sold out by the time you read this. If you can’t make it to San Diego, check out a local or regional comic con.
If you’re in the Los Angeles area, Stan Lee’s Comikaze Expo is coming up in September and Long Beach Comic Con in November. Or visit one of the smaller shows like the bimonthly Los Angeles Comic and Sci Fi Convention. [Edited to add:] Here are my write-ups & photos from last year’s LBCC 2011 and Comikaze 2011, both of which I’d recommend. I haven’t been to the smaller LA Comic/Sci-Fi Con in a few years.