Making a Feed Where None Exists

If a site provides an RSS feed, it’s easy to grab it for whatever purpose. (Perhaps too easy — as the blogger at RSS Specifications points out, echoing Tim Bray’s serious concerns.) But I digress.
What if the site you visit hasn’t created its own RSS feed yet?
Several tools exist to meet this purpose. One I’ve just been clued in to (thanks Nick) is called FeedTier. Give it a web page and it will do its best to parse the page into content and fluff and create an RSS feed of the content. In a few trials, it did pretty well, though it erred on the side of omitting good content rather than providing unwanted fluff.