This is the number one resource I provide when teaching about online discussions. This resource provides tons of examples of different types of activities you can do through online discussion boards, as well as provides the basics of discussion board facilitation pedagogy.
This is one of the most important articles about online discussions. It covers what happened when three different discussion facilitation strategies were used and how that impacted student participation. This is a must read as you decide how you intent to participate in the online discussions along with your students.
This article discusses how to use blogging tools to extend the conversation outside the physical classroom. Blogs are an excellent tool for discussion when you want students to publish their writing and then discuss.