...value for free:
Shareware and Free Software incl. Code Samples for the HC12
Tom Almy's HC12 Simulator SIMHC12 is implemented in Java
MiniIDE is an integrated cross assembler for the HC12/HC11. It also incorporates an editor and a serial communication terminal. Very cool program!
On Karl Lunt's Homepage you can find another Crossassembler for the 68HC12. The Amateur Robotics Fan also has created an HC12 version of his SBasic Compiler.
The universal Makroassembler AS from Alfred Arnold is a good choice if you're looking for an HC12 assembler
CANchat contains demo code showing how to set up both the internal msCAN module (HC912D60) and an external stand-alone CAN controller (SJA1000 on a HC12compact) - assembly language (use Makroassembler AS, see above)
GCC everywhere: GNU Development Chain for 68HC11 & 68HC12
HSW12 - HC(S)12 IDE for Linux including assembler, terminal and tools - by Dirk Heisswolf
Apple related: OS-X Tools for the HC12 - Rob Barris presents the AS12 assembler, a GCC 68HC12 install script and the SRecCvt tool for the Mac
FreeRTOS.org FreeRTOS is a portable, open source, mini Real Time Kernel with ports for a number of microcontroller families