FeedBurner, spotted a while ago but just now posting about, is a new service that proxies syndication feeds (RSS, Atom), and does various transformations on them. For example, if you only want to bother with an RSS 2.0 feed, they'll transform it into an Atom feed. According to John Battelle (2 ts, 2 es, 2 ells), they can also provide readership statistics.
Interesting but tricky model. FeedBurner is essentially providing canned computation, which is fraught with all sorts of DoS issues. However, since the computations are transformations, transformations created by FeedBurner no less, and not arbitrary computations, e.g. random script, I'm sure limiting resources is much easier. I'm sure there's some interesting distributed programming issues in the background there too.
I'm not quite sure about outsourcing the URL of one's feed, but apparently if you've got some server chops, you can use an HTTP temporary redirect to use the service, but keep your URL.