Some of the projects on we work as developers and/or committers
JForum
JForum is the most widely-used Java-based Open Source forum management system.
XStream
XStream is an easy to use framework for manipulating XML, used in many projects and products, both Open Source and commercial.
VRaptor
VRaptor is an MVC controller framework for web applications, based on the principle of "Convention over Configuration" which has contributed to the success of frameworks in other languages such as Ruby on Rails.
Tubaina
Tubaina is a textbook generator which receives a simple markup language syntax and outputs Xhtml and Latex.