Edited 15 November. David pointed out that I was in fact missing the feed icon:
Once upon a time, RootsWeb had feeds for the mailing lists, too. They ditched that plan after a trial run.Thanks David!
If you use Firefox, keep an eye on the address bar. The RSS icon will appear whenever a page with a feed loads. In the case of the message boards, view the source of the page and you can see the feed in the HEAD.
I use Google Reader and added a "Subscribe" button to my browser toolbar by following the directions found under the Manage subscriptions > Goodies tab > Subscribe as you surf. Simply drag the button to the tool bar! I have had the button for months and use it to subscribe to blogs quickly and easily but had never tried using it for anything else. I'll no longer have to remember to check the boards that I follow, now they'll end up in my reader.