Many of us still don't really understand when and how to use Web 2.0 technologies such as blogs, wikis, social networks such as Linked In, and del.icio.us-type social bookmarking. Still others use these personally but are unconvinced of their business value to governments, corporations and non-profits. While there are lots of definitions online for these (e.g. at Wikipedia), some of the best explanations for all of these technologies can be found at The Common Craft Show. Their short 2-4 minutes "Paperworks" videos on each topic are entertaining and well worth a few minutes of your time. Check out this video explaining blogs.