Mind Mapping software is often categorized as "project management" software (e.g. Wikipedia). Since nearly any productivity/planning software could be categorized as project management software, I think that it makes sense for this Wiki to keep most of these software categories at the top level.

I've been using MindMeister for a few years now. It is simple and awesome for quick mapping. Using a mapping tool has really changed my planning and thought process. If you havent started mind mapping, get on it!! Its great for todo lists, outlining an essay/article before writing, brainstorming, feature lists, and any idea-catching processes.... endless uses. Even mind mapping on paper is guaranteed to help you organize your thoughts better.

I've used MindMeister quite a bit as well and have found it very robust and easy to use.