Mind Mapping is a technique that allows users to create relationships out of pieces of information. It is extremely useful when a group of people are brainstorming a particular issue or idea and can be used to open up to ideas that you may not have normally thought of. It is a creative way to think around an topic and allows people to visualize thoughts and relationships in a meaningful way.
Historically, mind mapping (loosely related to concept mapping) started off with a group of people in a room standing around a blackboard/whiteboard and throwing ideas around. These ideas can then be joined to other ideas and spawn off sub-ideas, etc etc. A mind map application brings that level of interactivity and creativity onto your desktop computers. Mind mapping has a use both in the work space as well as at home.