This looks SUPER cool!
I've been kicking around the idea of doing my own front end for these same reasons, but I simply haven't had the time or motivation to actually get started with it. It looks like I'll just direct my efforts to helping you code this one. :-)
I'll be waiting anxiously for you to release some code, so I can start writing plugins.
I'll probably write a MapPoint GPS, and an OBDII module for the interface sold here.
I can't wait! :-)