There's a whole bunch of web-based applications like MindMeister (which is good, I agree with you). These are some more I know of: bubbl.us, bubble-mind.com, comapping.com, glinkr.net, kayuda.com, mapul.com, mind42.com, mindomo.com, webofweb.net

There are other free generic diagramming tools that can handle mind maps as well as Gliffy, like cumulatelabs.com/cumulatedraw/, flowchart.com and thinkature.com.

Most of these make collaboration easy, which is valuable. But I wonder about the security aspect. If it's a bunch of students working on a group project or a family gathering their knowledge of a family tree together, on-line is fine, but these services seem to be marketed mainly at the business world, and I certainly wouldn't want to put a collaborative business planning project, a team working on product ideas or business process thinking on one of these sites for the operator of the service to browse at leisure.

Some of these are offering a downloadable intranet option, and I suspect that most will all have to go that way if they are to make the money they presumably hope for.

Regards
Vic
http://www.mind-mapping.org
The master list of mind mapping &
information management software