Many years ago, I wrote a tool that logs OBDII and GPS data - it was one of the first around [pre-dates things like bluetooth ODBII devices and github], I never really focused on usability or anything, but what I made was cool: http://icculus.org/obdgpslogger/
The real enduring piece, though, was an OBDII simulator; I didn't want to keep going out to my car to work on the logger, and none of the other simulators out there were a) software, and b) supported most of the ELM327/OBDII protocol. So I wrote one.
The website isn't pretty, but if anyone actually wants to learn OBDII programming stuff, the simulator is still, AFAICT, one of the best out there: http://icculus.org/obdgpslogger/obdsim.html
The real enduring piece, though, was an OBDII simulator; I didn't want to keep going out to my car to work on the logger, and none of the other simulators out there were a) software, and b) supported most of the ELM327/OBDII protocol. So I wrote one.
The website isn't pretty, but if anyone actually wants to learn OBDII programming stuff, the simulator is still, AFAICT, one of the best out there: http://icculus.org/obdgpslogger/obdsim.html