The most advanced protection against sploggers and spam users registration, is fully WordPress,WordPress MU ,BuddyPress and bbPress 2.0 compatible

WangGuard Limited Registration Domain Add-On is an Add-on for WangGuard plugin. You can allow or disallow a list of domains.

WangGuard Blacklisted Words is an Add-on for WangGuard plugin. You can blacklist words.

WangGuard Registration Notice Add-on is an Add-on for WangGuard plugin. You can add a Notice in the registration page.