The Anime USA convention, "For Otaku, By Otaku", is coming up at the Hyatt Regency Crystal City in Arlington, VA over the Columbus Day Weekend (October 10-12, 2008).
http://www.animeusa.org/
Guests include Robert DeJesus, a pretty big name in manga circles, and local yokel Jo Chen, who does covers for Runaways at Marvel and the vast majority of the Joss Whedon-verse titles at Dark Horse, among other things, plus Allison Strom, who does manga work at Seven Seas Entertainment, Matt Herms, who works at Archie, and webcomics artsts of Paradox Lost and Applegeeks.
As with all of these Anime conventions, the price of admission is steep -- $40 through the end of September, and then I assume it goes up. I guess if you're going for the whole experience, that might be more reasonable than if you're me and just want to see the folks I just mentioned above!