I tried a couple of Bluetooth GPS devices that work with a mobile phone.
About a year ago, I got one (forgot the exact model) that worked fine, but did not give me enough accuracy, especially in streets with tree foliage. It also did not come with maps.

Now I am using the Nokia's Wireless GPS module (model # LD-1W), which comes with a phone app called Wayfinder, that supports maps world wide. You can get driving directions (with voice, similar to NeverLost), look up addresses, etc. It is pretty cool!

I haven't used it in an airplane though, since I can't use my phone there. Does anyone have experience with using a GPS receiver aboard a plane, to see the exact current location? Do airlines permit this?