Writing Your Own GPS Applications has a good intro to GPS programming. It covers the basic GPS commands and explains the terms you need to know when working with GPS. Examples in VB.NET with plenty of comments.
Not sure if I manage to resist the temptation of buying a Bluetooth Tom Tom much longer. Maybe I can integrate it with the SMS Bluetooth manager I wrote earlier this year? Or write a client on my laptop that automagically configures the IP depending on my location?