Basically you want your project to work 'out of the box'. When people are choosing the right open source project for a task, they download a bunch of projects that say they support the task, and use the best one. If a project needs significant work to setup (e.g. downloading 20 JAR dependencies from 20 different sites) most people will only either try it as a last resort or just ignore it.
Repository: You might try some newer repository engine - like Mercurial or Git. They ease development and ease merging of branches. Importantly though, choose an engine that is supported natively by your IDE.
Dependencies: You should use a readme to state dependencies, but this is not sufficient, either use Maven to manage dependencies, in which case you just need to include pom.xml file, or include JARs that you are dependent on in your distribution. In second case divide dependencies into mandatory, optional, compiletime and test. An example of an optional dependency are the bytecode generation tools for Hibernate.
Site: Maven may create a site that is associated with particular version of your software (never used that though).
Documenation - JavaDoc: Document everything, and try to enforce a policy that ensures high quality javadocs:
/**
* Sets the cost
* @param decimal cost
*/
public void setCost(BigDecimal decimal){
is useless. Better is:
/**
* Sets the cost, cost is in currency setted by #setCurrency.
* @param decimal cost, precision shoule be at least three places
*/
public void setCost(BigDecimal decimal){
Documentation: Javadoc is not enough. Give some starting point - a tutorial is preferable (and I don't mean the kind of tutorial with many screenshots of eclipse dialogs ;)). Example code is OK too, or at least write somewhere - 'Reading the javadoc of the EntryPoint class is a good way to start using this library'. If you have only javadocs anyone who is considering using your library will be presented a list of all the clases and packages, and will not know where to start.
Bugtracking Software: You won't remember more that three bugs at a time (and will forget things) - also it will help you manage tasks, and new wanted features.
You may want to try:
- FogBugz - its nice, but costs money. (Free for up to two developers).
- Bugzilla - nice, popular and free
Project Management Software: This will help you to calculate release dates, split tasks between developers etc.
Try to pass Joel test
Build process: Make the build a one-click process. For example an ant script that increments the version number, launches maven builds, deploys the site and so on. Worth the effort!
Forum: A nice idea, will help support.
Wiki: In many (even quite developed) projects such wikis are rather empty which is bad (as it makes people think 'how can this be great software if no-one writes in this wiki').