Since the beginning of the year I have now written about 20 blog posts, and have actually enjoyed writing them. I think having your students write blogs about different topics they enjoy writing about is a great idea. Rather then having to listen to a teacher inform you about a topic you have absolutely no interest in, you get to express your feeling about something you like. Also, I think that having the freedom to blog about anything in the world allows you to be more creative and can result in a better grade.
If you disagree and think that the teacher or students should have a say in what you write about, you can have two students and your teacher think up blog topics and share them with everyone. Then you can have the choice to choose one of those topics or write about something you think is more interesting.
Overall, I think blogging is a great modern way of expressing how you feel thorugh creative writing and is a great form of teaching.
I commented on Alex's newest post.