I've spent a lot of time exploring del.icio.us. At first I thought the only use would be another location for my favorites. I didn't see anything social about it and I liked rollyo better. I was hesitant about using the info I was finding a-c I didn't know who was posting and whether the source was accurate, authentic, etc. But after reading and using some of the Discovery Resources I began to be drawn into the "social" aspect. I've since added two feeds into my bloglines account. AS IF Authors Support Intellectual Freedom, a blog, which I found when looking at tags for IF. Then, of course, del.icio.us's sjlibrarylearning2 tag has an RSS feed. I see that del.icio.us is a way to keep up on the latest info for those topics that interest you or that you are researching. And I found WEMTA's president is also a user. One could really "stalk" someone if one has the time. Also, was able to add my tags to this blog.
Since I'm retired I am able to explore, but I'm not sure that if I was still working that I would use del.icio.us that much. I think that I could recommend it to teachers especially those taking classes. Not sure about students. I'm still planning on looking at how del.icio.us is used by libraries.