Using the GPS board I recently mentioned, and a Raspberry Pi, I built a stratum 1 NTP server. I'm working on a writeup of the process, in the meantime, here's a photo of the setup.
The red wire is used to bring the pulse-per-second signal to the Raspberry Pi GPIO connector (in this case, GPIO 18, but you can use a different line if that is already in use). The GPS is powered by the Raspberry Pi via USB, this also provides a ground return path for the PPS signal. At the same time, the GPS boards appears as /dev/ttyUSB0 to the operating system on the Pi.