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
I'm a delicious user and used to use a tag as you describe. I almost built this on top of delicious but decided against it as I didn't want to have to add the delicious signup as a requirement and then have to explain what delicious was.
I really like the idea of being able to use it without signing up - seems obvious now you mention it! Will look to add that shortly.
