A Flash-based mindmapping application. Functionality is somewhat limited (for example, while you can create an account and save your work, I don't see any way to export your maps, and there is no undo if you delete a node), but it is a fast and slick interface, good for casual work. Sort of like a fancy-looking version of FreeMind (an excellent program)

I had a go last week and, like most of these things, I waiting for a compelling reason to use it.