When I kept a blog detailing my experiences dealing with the teacher certification process here in MI, I would often get random comments from readers and I absolutely loved it. Like most bloggers, I was really writing it for myself, but to know that a) others were reading it and 2) others were enjoying it made me feel like I was putting my time to good use.
Commenting is an extremely important tool for educational use. In the one online class I've taken, commenting played a major role. Because we were using a university maintained community, we were posting under our own names, but the distance introduced by using the internet allowed people to speak their mind without actually being anonymous.
I'm not sure how well commenting would work in a class where the students see each other in person everyday, but I feel it would be worth a try.