Free 32/64/16-bit multi-platform Pascal and Object Pascal compiler
A 32/64/16-bit Pascal compiler for Win32/64/CE, Linux, Mac OS X/iOS, FreeBSD, OS/2, Game Boy Advance, Nintendo NDS and DOS; semantically compatible with Delphi, Borland Pascal and Mac Pascal (partially) with extra features, e.g. operator overloading.
multi-platform cross assembler for 6502/6510/65816 cpu
ACME is a free cross assembler released under the GNU GPL. It can produce code for the following processors: 6502, 6510 (including illegal opcodes), 65c02 and 65816. ACME supports the standard assembler stuff like global/local/anonymous labels, offset assembly, conditional assembly and looping assembly. It can include other source files as well as binaries while assembling. Calculations can be done in integer or float mode. Oh, and it is fast.
libTiMidity is a MIDI to WAVE converter library that uses Gravis Ultrasound-compatible patch files to generate digital audio data from General MIDI files. This library based on the TiMidity decoder from SDL_sound library.
RPilot is a GPL'ed implementation of the IEEE-standard language PILOT. It is an interpreter written in ANSI C, and will work on any system with a standard C compiler