Since making a very vague post regarding mind and concept mapping, I did very little to actually explore them, being rather busy with work and personal matters. However, I saw the perfect opportunity to jump in with both feet when I had to start writing some documentation - from scratch - regarding our clusters. Being cheap and still unsure of the utility of mind mapping, I grabbed a copy of FreeMind. It works quite nicely on my various Mac machines, and when I was one day forced to use my Linux box as my main workstation (my G5 was busy thrashing backing up a faculty member's Powerbook) that machine ran it quite nicely as well. I played around with it a bit in order to learn a bit about its interface and how it liked to do things, then got to work actually using it.
However, being an old-fashioned and tactile kind of guy, I have a large blackboard in my office, so I started there first. FreeMind seems to like to start from a central node, so I wrote down Clusters and worked from there. Soon I had a list of the various "chapters" I wanted to cover roughed out on the board, and I transferred that to FreeMind. For a while I worked back and forth, duplicating effort on both mediums, until I was relatively satisfied with the concepts that I needed to cover.
FreeMind has an export to HTML option, which produces a fairly nice list - collapsed or not - of the various nodes. I expanded nodes one level deep, exported that, and printed it out (see above, I like reading dead trees). Working with the printout, I created a series of text files, each covering a single concept or group of concepts: Administration, Compilers, User Accounts, Hardware, and so on.
I've not yet completed the documentation, but I can say for sure that this sort of mind map was invaluable in getting it started and in keeping me organized during writing. User documentation lends itself well to this sort of thing, so work is rapid. I have yet to try writing an essay outline with it - oddly, while an undergrad I was never big on essay outlines before the fact - but I have one coming up Real Soon so I might give it a go there. I can also say that the map was useful when creating my cluster presentation, as it allowed me to see at a glance which bits were likely to be important to my users so that I could ensure they were all covered in detail - no more and no less than they deserved. Since the presentation seems to have gone well, I will praise mind mapping for allowing me to get the whole thing done up in far less time than I would have thought.
Individual mileage may vary, but I'm definitely enthusiastic about the utility of this class of program for myself.