My b2evolution Version: Not Entered

There's an excellent spam fighting tool called Spam Karma 2 for WP here
http://unknowngenius.com/blog/wordpress/spam-karma/

The author has not licensed it as GPL, but he is open to allowing it to be ported to other platforms.

If anybody is interested, you could possibly write a port of this excellent script since I used for a year or more and it's been the best anti-spam tool I've ever used on my blog.

It's the only thing I miss from WordPress. :)