BuddyPress.org

I doubt it would be easy to integrate WP-United, phpBB3, and BuddyPress. It certainly sounds like it would work in theory, doesn’t it? However, these people don’t seem to be reporting much success:
http://www.wp-united.com/search.php?keywords=buddypress

I’ll give it a try tonight, and let you know what works and what fails.