I wasn’t aware of this, but vBulletin message boards provide RSS feeds. Then again, I haven’t spent much time on message boards because, up until now, I didn’t know that some of them had RSS feeds.
To get the feed just add
external.php?type=RSS2 to the URL, so for the TiVo Community forums at http://www.tivocommunity.com/tivo-vb/ the RSS feed is at http://www.tivocommunity.com/tivo-vb/external.php?type=RSS2
It looks like this is only for vBulletin 3, so no RSS feed for The Awful Forums unless they upgrade. Also, site admins can turn off RSS feeds, so it won’t be for all message boards. You might clean some insight from the official documentation, but it’s pretty sparse. Not surprising, there’s a good overview in their message boards.
What’s odd is that even when the site admin has RSS enabled, it doesn’t appear to add RSS autodetection to the site. I don’t know why you would want to hide this great feature.