Gwydion Sheets
- Gwydion Project's hypercode programming environment for Java supports complex hypertext interlinking, multiple groupings of code, and searching of code and documentation fragments. [Open Source, Public Domain]
- http://www.cs.cmu.edu/afs/cs.cmu.edu/project/gwydion/docs/htdocs/gwydion/Sheets/

Schmortopf
- A freeware Java IDE. Source available too.
- http://www.snowraver.org/java/Schmortopf/

Red Hat Source-Navigator
- A source code analysis tool. With it, you can edit your source code, display relationships between classes and functions and members, and display call trees. [Open Source]
- http://sourcenav.sourceforge.net/

Ginipad
- Integrated Development Environment for Java, written in Java itself. It provides syntax highlight, automatic code completition, edit-compile-execute cycle. It require JDK 1.4. [Open source]
- http://www.mokabyte.it/ginipad/english.htm

jEdit
- Programmer's text editor; includes support for dynamic download and installation of new plugins from a central plug in server. Java, XML and JSP source are well supported.
- http://jedit.org/