overunity.com should create a hard coded version of popular topics which summarizes, in article form, of most of the content's hardpoints. This would create a springboard for the search engines as well as bring visitors from those engines to the site.
The forum is getting what I like to call 'sedimentary buildup'. I wouldn't know which topics are most relevant because there is no mechanism except 'sticky' which highlights some of the important items at the top of the forum sections in the information box - this section contains "all topics related to use this discussion board" ...which could just as easily include links to the important highlights of the forum section as mentioned above.
Doing these two things may improve visitor signups to use the forum while allowing seperation of content for use by webcrawlers.
The spidies that aren't listening to your robots.txt file have actually NEVER listened to that file or the Meta information - blame terrorists and greed. Just as well though, you may be able to block them at the IP level with .htaccess, this would require moving the index of the forum, and creating a new main page while putting the forum in it's own directory