I have used most of the major documenting tools on the market, both free and otherwise, and find that it is almost impossible to write comments that are legible in both the source code and the documentation, finding that arcane means are required to get the style I need.
Yann L seemed to be having a similar problem, and one of the replies he got (I can't seem to find the thread in question) told him to use NaturalDocs.
After some initial annoyance (directories with spaces in seem to confuse it) I found it wonderful - mainly because it used a similar "english" way of laying things out to the way I was doing it before.
As my hands are getting less useful, this saves me a huge amount of post-documentation work[grin]