What is social bookmarking?
Social Bookmarking is a way to share websites with others and find resources that others have bookmarked. With tools like delicious, you can develop your own collection of resources organized with tags. You can also find others with similar interests and discover new resources.

What makes this great is that it is a way to filter information. When you search for something on Google, you have to rely on the computer to tell you which is the most relevant source you are looking for. But with Delicious, you are using human sifting, be it a few trustworthy colleagues in your network, or the entirety of the world's Delicious users. And, you can be given updates when new resources are found.

Lee Lefever gives an overview of social bookmarking in plain English.

Tagging is extremely powerful in web 2.0 technology. It represents a shift from taxonomy, where everything is classified into hierarchical categories, to folksonomy, where everything is classified with key words created by individuals.

Once you have found some sites and started tagging, you'll see there are other powerful ways to glean information from other people. You can subscribe to a tag, and you can create a network of colleagues.

Social Bookmarking Sites

Setting up a Delicious Account, Bookmarking, and Tagging

Networking with Delicious

Educators on Delicious

Delicious4Teachers (site of different educators using Delicious)

Other extensive resources on social bookmarking
Teacher Hacks
Classroom 2.0
Web 2 Tutorial
Jeff Utecht Tutorial