I'd like to spy on my car's CAN bus. I already have an OBD-II to bluetooth dongle that lets me use the Torque Pro Android app to see some OBD-II diagnostics, but I'd like to dig a level deeper and see the actual CAN bus messages. Googling has found some CAN hardware/software combos that are sold for this purpose, but I can't seem to find any that plug into the OBD-II port, and I'd like to use the dongle I already have if possible, though if that's not an option, I'll buy whatever works.

OSX would be my preferred OS for the software piece, but I'll do Android or (sigh) Windows if necessary.