I have been a great fan of Inspiration, the education focused mind mapping application, but the recently committed the mortal sin of launching version 8 which is not compatible with previous versions. It is quite expensive and does not have an online capacity.

There are now some very promising looking web based mindmapping applications that are free, at least in basic version, and have the huge advantage of allowing collaborative development of a map. A good review of three of them: bubbl.us, Mindomo, and MindMeister is found here in the Daily Web Worker.

The reviewer concludes that none of them have the full flexibility of the best tools, but are very promising. They rate MindMeister as the best, and it is still in private beta. Users can work on a map simultaneously, and can have a chat via Skype while doing it!

That looks as though these offer great educational potential. Another Web 2.0 success story in the making.