I couldn't post on your site, the reply buttons did nothing, probably too much modern JS or something. Saw some of the posts discussing accounts to avoid captcha and you could emulate the dial up BBS style of registration where it was just asking for a username and password + required you to answer some automated filtering questions. If you want extra protection just make it so all registrations have to be manually approved, but never make it require email or it will be dead in the water.