Lately I have been promoting Google Drawing as a great mind mapping tool...and it is, but sometimes it pays to use the real deal. Of course bubbl.us is a helpful (and free) brainstorming/thinking/planning tool, but it is an even better assessment tool. Next time you need to assess your students' learning have them build a mind-map of their knowledge. You'll be pleased with the results, and you can even post them on your website.