I have a webpage at my school that I have been updating but I think a blog could work in a similar way.  For instance, I have a link for a dialogue Prezi on my school homepage but I could do an entire post on dialogue and embed the link in the post.  The kids could access the post from home and complete the activity.
Another way I could use the blog is to communicate with parents about what we are doing in the classroom.  I could do a weekly post about homework expectations for the week and things the students will be expected to complete in class.
A third use for a blog would be for students to submit work to the blog.  For instance, we are starting to write original folktales.  It would be great if students could publish their stories on the blog and others could comment on them.