I run a few forums so I'm pretty familiar with spam bots and spam in general, and whats involved in a generally thankless job. That said I wanted to provide some feedback.
The current protection on this site is to only allow a new member to post once per 24hrs and then after a post count threshold they are free to post. Having been through that I found it to be VERY anti user. As a legit user, the restriction really inhibits someone from being able to engage, and I feel its really a turn off for new members and overall community.
On the sites I run, what I do is require the first 1 or 2 posts of a new user to require approval by a moderator. After they pass an approved post count they are no longer on moderation. This does a couple of things, first it allows new users to engage more quickly as moderators are checking the site more often than once a day. Second it prevents any spam from ever being seen by the users since the spam post will never be approved. Once I see a spam post in moderation I simply delete that bogus member and their posts. This keeps the site clean for the users, who also don't like to see spam, and allows new legit users to engage more quickly.
Just my .02, thanks for the site