As part of their 4th of July sale, Geeks.com has two bluetooth GPS units on sale for some ridiculously low prices.  I haven't used either, but they should work on the Nokia 770, if you just bought it.  They have the same specs as mine that works great.

UPDATE: Word over in the tablet forums is that the bt-5 is an unbranded Unitraq BT-5321R that works with the Nokia800.


BT-5 Bluetooth GPS Satellite Receiver w/Car Charger @ 32.99


Bluetooth GPS 20 Channel Receiver w/Sirf Star III @ 49.99


Deluo Wireless Bluetooth GPS w/Streets & Trips 2007 @ 92.99


If you haven't shopped Geeks.com, they are quite reliable and ship things very quickly.

Some other more expensive GPS units are listed below:

Garmin GPS10 (sensor only) @ 118.62 shipped, the Deluo GPS @ 112.72 shipped, or the Deluo GPS with DVD @ 114.76.  I've heard good things about both of these, but for your own peace of mind, as they are somewhat expensive (although about the lowest prices you'll find for this quality) buying from Amazon makes returns relatively painless.