Great Cow BASIC is an open-source BASIC compiler for 8 bit Microchip PIC and Atmel AVR microcontrollers.
I have posted demonstration code for 8 bit Microchip PIC and Atmel AVR microcontrollers http://sourceforge.net/projects/gcbasic/files/Demonstration%20Files/
Download the compiler from Sourceforge and you should be good to go with ease.
Anobium