Janino is a compiler that reads a Java expression, block, or source file, and generates Java bytecode that is loaded and executed directly. It is not intended to be a development tool, but an embedded compiler for run-time compilation purposes, such as expression evaluators or "server pages" engines like JSP.
fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists, and queues for Java with a small memory footprint and fast access and insertion. It also provides big (64-bit) arrays, sets and lists, and fast, practical I/O classes for binary and text files.
FM-Classic provides an easy way to get data from Java servlets into Web pages. It also helps you keep graphic design separate from application logic. The template language is powerful and intuitive, the compiler is fast, and the output approaches the speed of static HTML pages. FM-Classic is a continuation of the FreeMarker 1.x code base.
JOELib/JOELib2 is a cheminformatics library which supports SMARTS substructure search, descriptor calculation, processing/filtering pipes, and conversion of different chemical file formats. It is written in 100% pure Java, and interfaces to external programs (e.g. Ghemical) are available.
OpenSymphony Workflow is a very flexible workflow system that can be plugged in to almost any need or existing application. Uses can range from document management to order processing to project management. It includes support for many different interface mechanisms (SOAP, EJB, Java Class) as well as persistence (EJB, JDBC, XMl, Ofbiz). It works in any J2EE container, including servlet containers (without EJB support).
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.