My goal is to build a kind of a mobile tracker. There are many different use cases you can think of but one of the obvious is a device, that is able to report where it is. This device can be put in your car and it could trigger an alarm, if the car got stolen. Actually it could tell you where it is.
Here is a nice GPS antenna for APRS mode that is easy to build yet offers surprisingly good performance in a compact size. Best of all, it uses commonly available components and materials.
Here is a farely simple way to connect your PSP to a GPS receiver. Basically, you just need to cut the USB cable and PSP remote plug, figure out which wires go to the connector pins, and connect them according to the diagram.
This project contains step by step instructions to connect and mount a GPS to a D200 camera without having to pay the high price for an off the shelf solution. The cable created is in essence the same thing as the Nikon MC-35.
Here is a description of how to modify the compactGPS to work with a standard serial port. This mod will allow you to use the device using your PDA serial port, a PC serial port, and a PDA/GPS car kit.