Library 2.0 & del.icio.us

I really like del.icio.us. Every time I'm reminded of this site, I realize how much I really like it. But I just don't use it very often and I'm not sure why. But I think a web-based bookmarking site is awesome and such a great idea.
I've been reading about the concept of Library 2.0 for a couple of years now. I think in general, I appreciate the concepts that Library 2.0 describes. I'm not sure how new some of these concepts really are, but I don't think it hurts to have them described as formal concept to encourage service and innovation.