Funnily enough since you posted this thread, bot registrations have quadrupled on a daily basis! It appears that the bots are detecting the user names or e-mail addresses you posted and are assuming that registration was successful; therefore they are all trying to register?
Luckily bots are stupid and easy to fool.
Good thing too, I have enough things to do on this sites to-do list before it officially goes live without having to worry about stupid bots. Lets pray they don't figure out a way to fool the captcha.