Delicious reminds me alot of a site that I already use which is pinterest.com. While pinterest is a way to collect images and ideas, it also links you directly to the site that the image comes from, and you can organize into different boards, much like the stacks. (I actually found sites that people had saved onto delicious, that I myself had saved on pinterest.) I do like the idea of using these sites to collect ideas, and is a great way to organize the things that interest you.
Thinking as a librarian, which I like to do when I am doing these learning 2.0 tasks, I can see why these sites are helpful. IF you find something interesting at work, you can easily access the same site at home without having to send yourself a link or relook something up, which is such a pain in the butt. It is nice to have a place on the internet where all of your favorite sites are organized and easily accessible. As a librarian, you can use sites like delicious much like you would use an RSS feed. It is an simple way to keep your interests just a click away!
So in conclusion, I think I am going to stick with pinterest but can see why delicious is a popular choice.