CEManTIKA (Contextual Elements Modeling and Management through Incremental Knowledge Acquisition) is a framework to support context modeling and Context-Sensitive System design, in a generic, domain-independent way.
Tudu Lists is a J2EE application for managing todo lists. It's based on Spring 2.5, JPA/Hibernate and AJAX (using the DWR framework). It's a simple yet effective project management tool, and it is also often used as a sample Spring application.