Cathy Moore has a slideshow about how to plan for active learning – whether online or not. The key: concentrate on what people need to do, not what you think they need to know. Her slides would make excellent wallpaper for any instructional design atelier.
In the same post, she also says how she uses Compendium for doing her mind mapping. A quick download (Open University and others are behind Compendium) and peek later, I have it on my list of things to play with later. It looks pleasantly easy to use and flexible (you put down your ideas first, then connect them – no hierarchical connections from the start to deal with).