Check out A Fan's View
convention schedule. It's a pretty comprehensive list of anime conventions across the country. In OH, the 2006 list includes Ohayocon (Columbus), Pai-con (Westlake), Anime Punch (Worthington), Animarathon (Bowling Green), Matsuricon (Worthington), Harucon (Elyria), ColossalCon (Independence), and Ikasucon (Cincinnati). In MI, you have JAFAX (Allendale) and Youmacon (Troy).
Hope this helps.
Chris
PS - you might want to move this topic to the Anime Conventions thread.