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.
Luxor is an open-source XML User Interface Language (XUL) toolkit in Java that lets you build UIs using XML and also includes an ultra light-weight, multi-threaded Web server, a portal engine, and a template engine. It is also Web Start-ready, as everything fits in a jar and requires no loose files.
OpenEJB is a simple, lightweight Enterprise JavaBeans (EJB) container and server. You can embed OpenEJB in your own applications, or in a Web application server like Tomcat, or run it as a standalone EJB server. It supports EJB 3.0, 2.1, 2.0, and 1.1, and has partial support for EJB 3.1.
Spring IDE for Eclipse provides plugins for the Eclipse platform to ease working with Bean Factory configuration files for the Spring Framework. It contains a Spring project nature (with an incremental builder for validating Spring bean config files), an image decorator (which decorates Spring projects and all Spring bean config files), a Spring view (which allows one to browse Spring projects and their Spring bean config files, including bean properties), and an editor showing a graph from the beans of a single config file or a set of config files.
WidgetServer is a Java/XML server-side GUI-framework which enables an application to run as either a monolithic Swing app, a client/server Swing app, or as a Web app without any change and without loss of functionality. An Eclipse Plugin is available as well. A rich widget set is supported that includes tree views, tabbed panes, split panels, and much more. Animations, all types of events, and several effects are supported, as well. A unified widget-based, object-oriented programming interface for Web and Swing GUIs is offered to the developer to control and assemble the GUI. Web applications are fully AJAX enabled. For Swing client/server applications, the framework handles client/server communication, including compression and security layers.
Spring is a lightweight Java/J2EE application framework based on code published in "Expert One-on-One J2EE Design and Development" by Rod Johnson. It includes powerful JavaBeans-based configuration management applying Inversion-of-Control principles, a generic abstraction layer for transaction management allowing for pluggable transaction managers, a JDBC abstraction layer, integration with Hibernate, JDO, Apache OJB, and iBATIS SQL Maps, AOP functionality, and a flexible MVC Web application framework with multiple view technologies. There is also a .NET port available.