I recently picked up the book Reach, by Jeff Utecht, while attending BLC10 in Boston. I proceeded to read it very quickly, finding it contained many quick resources for teachers. I am going to share it with my staff at school. I had the opportunity to hear Jeff while at BLC10 and found his information to be practical and helpful. This book is both.
In the book, he shares information about communities and networks and how to make these communications work for you. He starts with the RSS feed and shows how it works for gathering information from the sites to which you subscribe. He provides tutorial videos and other information that can be helpful.
He also adds material on how to contribute to your learning community. There is everything you will need to help you start and set up a blog, wiki, ning, or other place to share your knowledge and experience. Again, he provides resources and support in the book. Along with that, you'll find information to help you build your personal learning network. What you need to effectively use Twitter, Skype, Facebook, and others is described and shared.
Jeff's book is a great place to start if you are getting just beginning in the area of using technology to learn and share with students and teachers.