I have their AFR sensor in my car, and have written some code to interpret the data. It's been baked into RomRaider and SSM Suite (
http://www.romraider.com/ and
http://www.codeplex.com/ssm) so if you have a Subaru you're in luck. If not, they're both open source so have at it.

It should be really easy to add support for other sensors - just a few lines of code to do the conversion to the appropriate units.