I tried to add http://opensnow.com/dailysnow/tahoe as a feed, but the feed validation step failed:

"It looks like this is a web page, not a feed. I looked for a feed associated with this page, but couldn't find one. Please enter the address of your feed to validate."

As it turns out, there WAS a little 'rss' icon, but of course it doesn't show up when I search the page for "RSS" and I have a hard time seeing the little tiny icon. When I finally found it, its URL was simply the original URL plus "rss".

Seems like it's pretty simple to add a recover step to the feed validation failure routine that tries "URL" + "/rss" before it totally gives up and reports failure to the user.