I say just buy a scangauge. I keep finding more and more useful information on mine every day. I just wish I could display more than 4 lines of info. 6 or even 8 would be nice.
Get an OBD2 streamer and a craptop.
I'm going to be getting an OBD2 streamer and writing a program for my windows mobile phone so I can scan codes, clear them, view live data, and log data as well. When I get a car that's worth a crap I'm going to build into the program the ability to change ignition timing and such too.
dkjones96, I'm very interested in your project...been looking to do the same thing. I was thinking of getting something ELM327-based and seeing if I could add a couple auxilliary inputs to it, or work them into an existing program to come in through another port.