ishiyakazuo: I am more a software guy than an hardware guy, if you can design an AT90CAN PCB with I/O for LCD, buttons, and all the pins for ISO, VPW, CAN, etc, it would be cool of course
For the moment I will go with the Arduino+ELM327. It's a solution that can work for *all* protocols.
Be careful of the chinese ELM clone on eBay, a lot are using the old 1.0 revision illegally cloned on a PIC...
OBDuino 1.0 version can be Arduino+ISO(+VPW), minimal hardware
OBDuino 2.0 version can be Arduino+ELM327 or AT90CAN, more expensive but you need this for CAN, meaning if your car is 2008+ (and some earlier) only.