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.
Jiim is a Web-based Instant Messaging system that overcomes the language barrier, letting you read and type in your mother tongue.
MyOPM is an Online Property Management system for small and mid-sized real estate businesses. It provides a back-office suite tailored to the needs of real-estate businesses.