I've been a big FreeMind fan for years. Durring my wife's first year of law school, I persuaded her to try using it for one of her classes. She proceeded to quickly adopt it for all of her classes. Having a mindmap of an area of the law at 30,000 feet, and then be able to zoom all the way down to the minutia was very valuable.

Her peers started adopting it themselves after seeing her "outlines" in study groups. Great tool!