Does anyone make a navigation device with no GPS receiver...
 

...but will accept NMEA input on a serial cable from another GPS device such as the Origin B2 that I'm about to get.

I'm looking to replace my Garmin StreetPilot III with something less bulky and don't really need to incur the cost of having a 3rd bloody GPS receiver in the car.

I'd like something which is a nice flatscreen I can install into my dash, possibly touchscreen though this isn't important, basically I want the money saved on the GPS to get me a bigger screen.

I'd prefer to avoid the PDA option (unless anyone makes something for the Nokia 9500) as I don't want a PDA and they never boot straight into the navigation software and even when they do they seem a bit clunky (well, the Medion one does) I also dislike the stylus for car use.

Most software will accept the GPS data in NMEA format, the device supplying it is irrelevant. You do need to be careful though, I wanted to go this route myself with Road Angel and a PDA and it is messy. The output from the RA is RS232 and the PDA takes USB only. IIRC the PDA acts as a slave so needs a master source, which you can't do with RS232 converted to USB. I then tried to go RS232 to bluetooth but that was looking expensive.

In short it possible, but research what you have and what you need to buy to make it work otherwise you could spend a lot of cash with no result.

This is why I was asking if anyone made something specific.
I personally would like to see automotive GPS devices go down the route where none of them have a GPS but they all have an NMEA in and a passthrough. Then car makers can put the GPS in a sensible place like the middle of the roof and all the devices become cheaper.

The other option I was considering was a Mini-ITX based PC with a 12V PSU and a decent shutdown controller or small UPS. I have an NTSC kenwood LCD panel with composite in that could be used in conjunction with the TV out on these things, and gives me the added bonus of hard-drive based MP3 playback, the only problem is building an interface for it all. I could ditch my sony MP3 headunit though :)

You thought about using a compass and map?

I have TomTom on my PDA, but the GPS signal comes from Garmin Etrex via NMEA. Allows me to connect and disconnect when I want, and means I can navigate somewhere in the car, disconnect it, and use it on a nice long walk too :)

This is basically the way it has gone with marine navigation systems. Plotters can be purchased separately from the GPRS module and talk via NMEA. In fact just about all modern navigation instruments can be networked via NMEA now.