I've used BLIPMAPS, XCSkies and other forecasting tools on an HP
netbook sold through Verizon. The height of the screen is ok but not
great for maps.
Have not connected it to a GPS.
The netbook gets online all over the place, and connection speed is
decent. It has USB (would require the same adapter as other computers
without serial port) and an SD card reader. It fits easier than any
other laptop in the baggage compartment or perhaps even behind the
seat.
Jim