A long time ago, I brought up social bookmarking and promised an article. I started one but being I apparently suck at writing and am lazy/busy, it remained in an unfinished state. Fortunately, some one way more ambitious than myself created a video explaining it. It's relatively short and gives a good background of what it is and why it's helpful. For those curious/interested in it, take a view:

http://www.youtube.com/watch?v=x66lV7GOcNU

I can help answer any follow up questions on the subject.

Not entirely unrelated, but I noticed the guy that did that one, also has one explaining RSS:

http://www.youtube.com/watch?v=0klgLsSxGsU