colorForth is, in Chuck Moore's own words: "A dialect of Forth that uses color to replace punctuation. Includes its own operating system. Produces extremely compact programs. Instant compile from pre-parsed source."
The Portable Forth Environment implements the ANSI Forth Standard,
it is fully written in C, the newer version has a module concept,
and it is fully multithreaded. Autoconf used. Tested in embedded environments.
Calforth is a variant of the forth computer language. It will run as a forth interperter, as well as strictly compile an executable. Version 1.3 includes support for the 8051 processor and includes a processor emulator as well.