I'm using the same GPS unit as electrolind, the Holux M1000. Its the first time I ever owned a gps device, and I can't imagine anything being better. It pairs with the N800 perfectly, and works perfectly with MaemoMapper. From switch on, the GPS locks in to a satellite in <10 seconds, its accuracy is usually perfect except for severely bad weather. Works indoors as well, including my work which is under a steal roof.

It usually lasts me at least a day or two, in which i keep it on and in my jacket breast poket so it follows me where i go.

If you can find it, but it, its perfect as far as I'm concerned.