1. Runs obdgpslogger, combines OBDII and GPS info together and logs the output. Can be queried for information about either.
2. Fusion brain control
3. Boomzbox HD radio control
4. XM/Sirius radio control
5. Mediatomb or any Linux based upnp player can serve audio and video from a USB external drive
6. OSDash client
Basically, the idea is to have the embedded Linux device (either Sheeva plug or igep v2 or the upcoming Beagleboard XM) interface with the outside world and provide a way to communicate that to the Front End.
Running an Apache web server on it, you could serve up a web page inside the FE that allows you to control the functions on the Sheeva, or if you want, you can code that stuff into the FE.