I've really been happy by student response to blogging in the Chaos and Fractals course (although I didn't start up the blog until late in the semester, with a resulting small number of student posts.)There's enough here for anybody teaching from K-16 and beyond. Many of the sites have opened my eyes to different teaching and learning techniques, and blog designs that assist these techniques.
This is the second year of the Edublog Award blog, so you can check out last year's winners via the archives.
While you're at it, check out Incorporated Subversion, James Farmer's blog. Farmer is a designer, educator, writer and consultant living and working in Melbourne, Austra ...At his blog you'll see several of his initiatives, including free blogs for university students (uniblogs), educational blogs (edublogs), and social software and open source for education.
(Note: I got the idea for this post after reading a nice summary of the Edublog awards by Joyce Kasman Valenza in the Jan. 22, 2006 Phila. Inquirer)