A few years ago I wrote about a project I developed for my then employers, which I open sourced under the name CaseBook. The intent was to single-source end-user documentation which could be be transformed into internal and client acceptance test scripts. As I developed it, the project involved XML, Schematron, XSL and XQuery, hosted in an eXist database and accessed using webDAV.
At the time, I had barely heard of DITA, the Darwin Information Typing Architecture, but the approach I took shared some ideas with what I later came to learn about DITA, using concept maps, separation of topics into tasks and steps and so forth. In the mean time, DITA has gained a lot of traction, and my SourceForge page has been hit maybe 500 times.
I have been giving a lot of thought lately to collaborative writing. As Anne Gentle has pointed out on her JustWriteClick 'blog, DITA shines in environments which have a strong collaborative or Agile approach, since both of these emphasize timely repurposing and multipurposing. One of the problems I was addressing with CaseBook was collaboration between development, documentation and testing resources. Now, in part, this was because I was working in a small team, and had responsibilities in each of these areas.
I still think there is a lot of value in facilitating collaboration between these groups, and were I to develop this project today, I would start with the DITA Open Toolkit from day one.
In addition, for the last four months, I've been working with Flex, mxml and ActionScript. One thing that intrigues me about mxml is that it is XML. For instance, what if you could generate end user, acceptance or client walkthrough documentation automatically from the mxml source? Transforming mxml to DITA seems like a useful technique.