Another toy in the truck? Yeup... But I think this one's REALLY cool.
(click for larger pics)
This is mounted in my truck:
It drives an XM receiver and knows MP3s/WMAs

(and there's a USB jack cut into the center console where I can plug in my mp3 player!)
Has WiFi support:
Has GPS support: (note the Lat/Lon in the left pic, and yes, that's MapPoint)
...an OBD II interface and calculator:
This is what's under the driver's seat to make it all work:

left to right: OBD II interface, USB hub (under OBD II box), AtoZ PC, power controller in front of PC, XMDirect receiver
(AtoZ has been replaced with a VIA M10000 - see links below)
What it all is...
- Hardware
- Software
- General info
The whole system's been out on two rough dirt runs and has done GREAT.
I tried doing this about 3 years ago but the technology just wasn't ripe yet. It is now.

This took about 4 weeks to get to run somewhat smooth, and a weekend to install. There are still some glitches, but a lot of the UI software is beta so it's to be expected.
WooHoo!
update 5.30.2007: new GPS bug; new OBD II adapter; added Boost phone; added bluetooth & 802.11g