If you have OS X 10.5 and are looking for a simple free mind mapping program, take a look at Mindnode. It is very basic, but that helps keep things very simple. If you want a good introduction to the mind mapping process, you should take a look at this book.
agh, times like these, I wish I had a mac!
@Terra – Take a look at Freemind. It runs on multiple platforms and might work well for what you need.