PIC Development System for Macintosh includes PIC disassembler, by MacRobotics. [Shareware]
http://www.macrobotics.com/MacPIC.html
http://margo.student.utwente.nl/el/micros/68xxx/6805v108.zip
A collection of open microcontroller (68HC811) software tools and hardware designs with PCB layouts and schematics.
http://www.ee.leeds.ac.uk/homes/NJB/Software/CREAT/creat.html
from Axxon.
http://margo.student.utwente.nl/el/micros/80xx/debug51.zip
Includes PIC disassembler by Jaffa Software. [Shareware]
http://homepage.ntlworld.com/rpsprowson/pics/
A fast, low-power, synthesizable RISC processor, which also comes with an assembler
http://www.geocities.com/microprocessors/
PICabc-visual assembler, disassembler and PIC tutorial provide simple method for programming PIC microcontrollers. [Commercial]
http://www.abc-micro.co.yu/
http://margo.student.utwente.nl/el/micros/68xxx/68hc11/mx11v2.zip