One of the activities in the book is called "Chain Notes", and would work well for a discussion board and maybe even a blog. Normally this activity starts with a question written at the top of a piece of paper, such as "What is matter?". The paper is passed around and each student adds one or two sentences to the list; adding a new thought or building on previous statements.
This could easily be adapted to a discussion board or blog. As the teacher you can pose a question, and every student can add a comment that expands on the answer. Students may also correct any false information. This would be a good way to review a concept at the end of a unit.