I have a suggestion to GPSApp- why not make a file (called Named Pipes or FIFO in unix?) that other processes can read from to get the current coordinates and speed (and maybe other stuff?) from GPSApp. I'm sure people can think of a lot of useful apps that will read the vehicle's speed and do something with it.
I have another feature suggestion to GPSapp also: Calculating the sunrise/sunset time for the current location. This information is very useful to me as an amateur photographer. I found some code that does this and I'm going to get it working on the empeg. If I get it into a function form would the author of GPSApp, jaharkes?, be interesting it into integrating into the UI for me?