As a teacher, the first use I would have for my blog as mentioned in Blogging in Language Learning would be to communicate with absent students. As a student teacher there was nothing worse than hearing "Srta Talty, I wasn't here yesterday wha'do I do?". On our class blog, I would post all class notes, assignments and due dates, and pdfs of any worksheets. Students would be responsible for any work they missed and if they came back to class without it, it would be graded as a late or missing assignment since it was on the blog and easily obtainable (within reason, obviously. I would not expect a student fresh from the hospital to complete assignments). I would also communicate with them via the blog if they had any questions regarding the posted notes or assignments.
Another way I would use a blog would be to create literature circles. Standard LOTE1 ML2 states that students should be able to use reading and writing skills to express personal opinions and feelings. Perfect! If we read a novel or short story as a class, we would discuss it (in Spanish, of course) using the blog. I would post some prompt questions on my page and let the students do the discussion from there. In class, we would then post the blog up on the smart board(a teacher to be can dream) and discuss some of the posts and comments.