Agile Documentation: Strategies for Agile Software Development
http://www.agilemodeling.com/essays/agileDocumentation.htm

Agile Modeling

Abstract:

When I initially started work on Agile Modeling (AM) I wanted to focus solely on principles and practices for effective modeling but quickly discovered that this scope was not sufficient, that I also needed to consider the issue of how to be effective at the creation and maintenance of documentation too. Some agile models will 'evolve' into official system documentation, although the vast majority will not, and therefore it is relevant to discuss how to be agile doing so.