Review http://browserpop.com
sheriff: My first instinct is that I can get 80% of the way there with a tag in my Delicious account.  The other 20% would be in a UI that was really geared towards being a home page.  As a result, it'd be great if folks could try out the interface without having to sign up first.  No reason you can't let people add a couple URLs to see if they like it, and only require sign up if they want to save their bookmarks beyond that browser session or access from another computer