Grails is a full stack framework for developing Web applications on the Java platform. It builds on the concepts introduced by frameworkds like Rails, Django, and TurboGears, but builds on established Java technologies like Spring and Hibernate. It includes an easy-to-use object relational mapping (ORM) layer, an expressive view technology, a controller layer, a command line scripting environment, an embedded Jetty container which is configured for on-the-fly reloading, dependency injection, support for internationalization (i18n), and a transactional service layer.
GreenMail is a suite of email servers for testing purposes and sandbox development. It supports SMTP, POP3, and IMAP (including SSL) and can be embedded into any Java application or unit test. The GreenMail Service (SAR) extension runs as a JBoss embedded developer mail server sandbox, manageable via JMX.
JCatapult is a development platform written in Java. Built for modularization, JCatapult allows developers to build modules such as a blog, content-management system, wiki, or any other reusable set of features and use them across multiple applications. Built on top of open source technologies, JCatapult is a robust and scalable platform. However, it is also agile and lightweight because it uses a convention over configuration approach.
The Apache Open For Business Project is an enterprise automation software project that includes ERP, CRM, E-Business/E-Commerce, SCM, MRP, and CMMS/EAM functions. It is a foundation and starting point for enterprise solutions and can certainly be used out of the box, but is also great for creating specialized applications.