I've been using Lefora, an interesting combination of forum and blog, for a while now as a language teaching and teacher training tool.
The video below shows some of the main features and some examples from my own Lefora forum:
It wasn't possible to cover all the features in a five-minute screencast, but I hope that gives you a quick overview of some of the main ones.
Definitely worth trying out - I've found it extremely useful for not only managing large numbers of students online, but different kinds of courses and even teaching tasks and materials.
:-)