Socialmarks is a new service that is a Social Bookmarking system (getting ready for Beta release) that will allow you to manage RSS/Atom Feeds and bookmark its posts with tags. But, it goes further. I would have been happy with just bookmarking the posts from the feeds, but with Socialmarks, you can even tag the RSS/Atom Feeds themselves. I really like this concept because instead of only websites being in the social bookmark system, RSS/Atom Feeds can be as well.