The ASF @ 15 - The Apache Software Foundation Celebrates 15 Years of Open Source Innovation and Community Leadership http://s.apache.org/wZr
... and cheered at ApacheCon Europe http://s.apache.org/1o4
The ASF is made up of more than 150 top level projects which cover a wide range of technologies. Chances are if you are looking for a rewarding experience in Open Source, you are going to find it here.
User-friendly Java ORM with tools
Cayenne is a powerful, full-featured, opensource framework created for developers working with relational databases. it seamlessly maps any relational database to Java objects, reducing development time and adding considerable functionality to any application which requires a database. Developers using Cayenne will be able to concentrate on the core business requirements and the data model instead of the SQL details. The application can then be easily moved to any JDBC-capable database. In addition to management of persistent Java objects mapped to relational databases, Cayenne provides a plethora of features including single method call queries and updates (including atomic updates of all...
The first free open source JavaServer(tm) Faces implementation.
MyFaces is the free open source implementation of JavaServer(tm) Faces, a new and upcoming web application framework that accomplishes the MVC paradigm. It is comparable to the well-known Struts Framework but has features and concepts that are beyond those of Struts - especially the component orientation.
Content Management Framework
Apache Lenya is an Open Source Java/XML Content Management Framework and comes with revision control, site management, scheduling, search, WYSIWYG editors, and workflow.