Re: Spam Registration
To prevent the registration in the first place, why not a CAPTCHA?
It could probably be added to a bbPress install with a plugin. Or, a while ago, Trent mentioned he added a couple of fields to his registration form, and the bots haven’t figured that out yet.
Also, it seems like the bots all tend to fill out the interests and website, but users normally don’t. Maybe you could add something to your template that says “Please don’t fill out this field” that a bot could not read, would fill out, and then you could write a plugin based on that?