Some more on using the RSS feeds.... you can "add" them together. For example, this is the RSS feed for the Community Board:
http://www.disboards.com/external.php?type=RSS2&forumids=33
And this is the RSS feed for the Theme Parks Board:
http://www.disboards.com/external.php?type=RSS2&forumids=2
So you can set up one RSS feed like this:
http://www.disboards.com/external.php?type=RSS2&forumids=33,2
That'll put the two forums together in one RSS feed.