I've started dipping my toe into the ocean of social bookmarking. Jason Griffey has an excellent introduction to del.icio.us in the Five Weeks to a Social Library - week 2. There are a few ways of following the lectures on this site but my preferred method is to download the talk in mp3 and then follow the presentation slides. Jason's talk (it lasts over an hour) is slow to start but the last 25 minutes or so is packed with useful information.
Inspired, I set up a delicious account for my library or LRC (as we call them in further education) and have started to tag the websites catalogued on our OPAC. It even works for journal articles we've catalogued from our datasets such as InfoTrac.
Now that I've got this far, I don't know what to do next with it. No doubt Phil Bradley will have a few pointers in his book "How to use Web 2.0 in your Library". Unfortunatley for me, social bookmarking doesn't crop up until Chapter 6 and I'm only on Chapter 3. Come to think about it, I'm still on week 2 of the Five Weeks to a Social Library and I'm sure I started that last February!