After a school in-service last November I decided to start a classroom blog. I love it! Since then, my students also created blogs off of mine (I have access to their pages and must approve any comments they get). Parents like the fact that their children are getting experience online with this type of guidance.
Through PT we met some blog pals. We did a few activities with them and then Skyped later in the year. We also followed other classroom blogs and learned a lot about geography by following where people were from who visited our blog.
I suggest you look at classroom blogs to see how people are using them. I do not post homework on mine - I use my school web page for that. I use mine to show and explain what we are doing in the classroom.
Here's the link to mine:
http://mbsteven.edublogs.org/
If you scroll down the middle column a ways, you'll see a blog roll with links to other classroom blogs.
Good Luck!