Another idea (which I'm currently using in my FZJ79) is to attach an iPad to your deck. Most decks nowadays come with USB support...so you can use the USB port of the deck to provide constant charge to the iPad battery. Connecting your iPad to the audio-video input of your deck, also enables you to use the iPad as a music / video device. Another handy piece of equipment (which you can also keep charged, if your deck has TWO USB ports) is a WiFi device (personally, I use the PTCL EVO Cloud, which enables 5 devices to be connected simultaneously). Once you have this WiFi device in your car, you should be able to do all sorts of interesting stuff...like live streams from Google Earth / Motion-X (for navigation), receiving and sending e-mail on the go, measurement of tilt and rake angles of the vehicle, actual GPS calculated velocity (rather than speedo measurements), live video streams from YouTube etcetera. In short...all of those things which the iPad is capable (which are an awful lot of things!). The setup which I have, incorporates a simple, cheap iPad leather cover, attached (with Velcro) to a home-made wooden cradle, which mounts on the FZJ dashboard, in place of the inclinometer / outdoor temperature gauge. When in use, simply slide the iPad into the case, and bung the WiFi device into the glove compartment. When you're parking...slide out the iPad and WiFi device, and take them with you. Bachon ko un ke saath ghar pe khelne ka moqa fraham karein! Aap bhi khush, Begum bache bhi raazi!
I'm told a good condition (used) 16 GB iPad costs something in the range of Rs 25,000/- or so. Believe me...it's money well spent. And if you have multiple rides, a similar arrangement in each of those rides will enable the iPad / WiFi setup to be used in whichever vehicle you're driving at the moment...which eases out the average initial expenditure per vehicle, even more. Alternatively, if you're an iPhone / iPod touch user, a similar (but much smaller arrangement) works wonders on a budget...providing all the marvelous apps of the iPad, at a slightly smaller viewing size. To slash the budget even more, one can always dispense with broadband WiFi and use the existing GPRS / EDGE connection of your phone's data plan for light browsing, etcetera. Of course, heavy data flows (for sat-nav, video streaming, etc) won't be really good unless you have a WiFi device in your car.
I am a great believer that our rides are almost an extension of our respective personalities. At the end of the day, thus, do whatever suits you and your pocket, and have great fun WHILE doing it!
(In this picture the red and black leather case in the almost-centre of the picture is the iPad cradle and casing)