jRapidRPC is a Java RPC library that allows you to create client-server applications that talk in objects. It is small, fast, and extensible. Its smallness helps you learn how to use the library quickly. jRapidRPC is fast due to its compact size and lack of complexity. Also, it uses the ProtoStuff serializer by default. jRapidRPC's extensibility allows you to can write a new client-server or a new serializer.
Jacman is a GUI frontend to ArchLinux's "pacman" package management system. It provides an attractive interface to the majority of key features of Pacman, including installing, removing, and updating packages. It also includes "rollback" functionality to return back to an older version if necessary.
Chaplin ACT is a Java class transformer which brings several modern language concepts into Java: contexts, composites, roles, traits (mixins), runtime type conversion, dynamic method signatures, method and field aggregators, etc. Using these concepts makes designing loosely-coupled applications and writing cohesive code easier. Chaplin can work either as a JVM agent or as a post-compilation class transformer. It does not introduce any new syntax. All functionality is implemented by means of the standard Java language elements.
Reverspring is a Java library that allows you to create Spring IoC XML files from POJO at runtime. CoI stands for Control of Inversion: Reverspring just inverts the inversion of control mechanism of Spring Framework, allowing you to (re)write Spring descriptors starting from your Java objects. With Reverspring, you can write process descriptors on XML files without reinventing a new DTD or XML schema, but just using the well known Spring IoC syntax.
Ammentos is a lightweight persistence framework for JDK 5. It does not require any installation nor configuration; just put a jar file into your classpath and start writing code. It is designed so that your persistence code will be dramatically short and so that you won't have to spend a lot of time to learn how to use it. It is about 72Kb large and it does not require any external library except for your database JDBC driver. You can use it in desktop applications or in server-based environments.