Blogging can serve many purposes. It can provide teachers a way to engage students, connect with parents, and engage in discussion with others. For some, blogging is just therapeutic.

Jessica's Blog
Web 2.0 Connected Classroom Blog
Committed Sardine Blog
Here's a nice list of blogs to inspire you!

Here are some great places to make a blog:
http://www.edublogs.org
http://www.blogger.com
http://www.wordpress.org