PicForth, a Forth compiler, generates code for the Microchip PIC 16F87x and 16F88x microcontroller families. It is hosted on Unix (or Linux) using GForth 0.6.x. It includes two kinds of cooperative schedulers. You can download PicForth 1.2.5 from http://www.rfc1149.net/devel/picforth . PicForth is available under the GPL free software license.
In the distribution, you will find some examples: a model railroad booster, a DCC signal generator, some code for silver card smartcards.
Be sure to check out the tutorial at http://tutor.al-williams.com
For some more comments + examples see http://tinymicros.com/wiki/PICForth.
See also rforth by the same author.
(For the the PIC 18F and dsPIC 30F processors, see FlashForth).