I first encountered the concept of mind maps when I read the 1st edition of "Extreme programming explained" by Kent Beck. I've wanted for a long time to delve more into this subject, but it's only now that I got around to it by reading "Mind maps at work" by Tony Buzan, the inventor of mind maps.
To put it briefly, a mind map is a graph-like structure that starts with a central image of the concept you're trying to focus on. You then start drawing branches radiating out from the center, and on each branch you write some quality or feature of the central concept. Then you draw smaller branches, twigs if you want, with more and more details pertaining to each branch. Since a picture is worth a thousand words, here's a mind map I drew while brainstorming about ways to approach automated testing (apologies for the poor quality of my handwriting):
The beauty of this is that I was able to summarize in a single page almost all the concepts that Titus and I presented during our PyCon tutorial! Pretty amazing if you ask me....
One thing that Tony Buzan recommends, and that I found very helpful, is to use different colors for the different branches of the mind map. This is because one of the main strengths, if not the main strength of mind maps, is to engage both sides of your brain -- and using color helps exercising the often neglected right side. The usual method of describing a concept by using linear lists and slides with bullet points is much more analytical, and tends to engage only the left side of the brain.
I find that when I draw a mind map by hand and when I use color, I tend to brainstorm a lot more, and I tend to find new associations between concepts. Because everything is on one page, it's easy to see the big picture and to start connecting things in sometimes surprising ways...
I even managed to get my kids interested in mind maps (lesson learned: it's much better to get your points accross to your kids if they see you doing something you're excited about, rather than just talking/preaching about it...). They've used them so far for inventing new video games -- I'm hoping they'll also use them when they study for Social Studies or Science :-)
I'm pretty excited about mind maps and I plan on using them intensively on my projects. Highly recommended!