A new, free service, currently in Beta testing called FeedTier offers the ability to scan a normal webpage and construct an RSS feed from it.
Try these out in your favourite RSS aggregator, or Use the File->New LiveMark option in Firefox’s Bookmark Manager:
GD:
http://feedtier.somee.com/?http://boards.straightdope.com/sdmb/forumdisplay.php?f=7
The Pit:
http://feedtier.somee.com/?http://boards.straightdope.com/sdmb/forumdisplay.php?f=5
GQ:
http://feedtier.somee.com/?http://boards.straightdope.com/sdmb/forumdisplay.php?f=3
Or roll your own at the website
The Straight Dope hopepage (http://www.straightdope.com/index.html) doesn’t work unfortunately.