I really don’t understand how this particular site is that useful. Unless you are really interested in another site and cared to see how many other people have added it, it doesn’t seem like it is something that a normal web user would need. It does save a bunch of sites that a particular group is interested in but for myself I don’t think it is something I would use on a regular basis.
I use it for all my bookmarks which means I can access them from any computer not just my laptop. Also if I log-in to Del. I can then use the “post to Delicious” button for any site/news etc. that I want. Del. will open and I can immediately add my tags and it is done.