Clozure CL is an open source Common Lisp implementation that runs on PowerPC hardware under Mac OS X and Linux, and on x86-64 hardware under Mac OS X, Linux, and FreeBSD. A port to 32-bit x86 is progressing well; a port to 64-bit Windows is also pretty far along. There's also a Solaris x86-64 port that is mostly working.
The Pencil Project's unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use
Trails is a domain driven development framework in the spirit of Ruby on Rails and Naked Objects.
JMatter is a software framework for constructing workgroup business applications based on the Naked Objects Architectural Pattern.
