Mindmeister Concept Mapping Tool
There are dozens of concept mapping tools available on the Web. Many are free and quite good. One that stands out is mindmeister. It is exportable in several formats, embeddable, and has many wiki-like features. For example, see a concept map of social media web sites. Concept maps can be used for anything from syllabi to collaborative writing assignments.
Related entries:
Coggle in the Classroom: Clean, Easy Concept Mapping
Using Visual Understanding Environment (VUE) as a Concept Mapping Tool
IHMC Concept Map Tools