Batik is a Java-based toolkit for applications that want to use images in the Scalable Vector Graphics (SVG) format for various purposes, such as viewing, generation, or manipulation. It gives developers a set of core modules (parsers, generators, DOM implementation) which can be used together or individually, and be highly extensible. It comes with a full-fledged SVG viewer.
BlueJ is an interactive Java development environment. It provides a unique user interface that presents a graphical display of the application classes and their relationships, and it lets users interactively create objects of any class. Once objects have been created, users can interact with them directly. This interaction mechanism allows for much greater testing and experimentation than in conventional environments. BlueJ is suited for teaching and learning OO and Java.
Apache Cocoon is a Web development framework built around the concepts of separation of concerns and component-based Web development. Cocoon implements these concepts around the notion of "component pipelines", each component on the pipeline specializing on a particular operation. This makes it possible to use a Lego(tm)-like approach in building Web solutions, hooking together components into pipelines without any required programming.
GNU Classpath (essential libraries for Java) is a project to create free core class libraries for use with virtual machines and compilers for the Java programming language. It includes all native methods and core classes necessary for a completely functional execution environment.
gnu.hylafax implements the HylaFAX client network protocol in pure Java. With it, Java applications can access a HylaFAX server in various ways, such as queueing FAX jobs, checking server/job status, and retrieving FAX files. The gnu.hylafax distribution also includes gnu.inet.ftp, a pure Java implementation of FTP client protocol (RFC0959).