Keeping your project documented can interfere with the ten other roles you must fill. I'm speaking from a perspective of the small software shop were you cannot afford to have one or more paid documentation experts (or QA or project management for that matter :)
The solution:
Maven can be a god send to a small software shop. I feel Maven often gives people the notion it is for use in big software shops. Not true. Just because large Apache Java projects are using it does not mean it is too much for a small library or application type project. Maven can create for you a full website, including reports on things such as test coverage, JavaDoc, PMD information, dependencies, email lists, etc. etc. This sounds pretty complex, eh? Well worry not it is simple, and I will show you how to generate such wonders... but in later posts. Let's KISS here. So you have a Maven project and you want a site generated, so just type the following and you will have a full site in the target folder of your project:
mvn siteDone!