There are free public domain applications to grab the time from the GPS module and synchronize all of your PCs to this NTP server. Search www.google.com for these applications.
Users use this GPS to record coordinates to a log file. Then you can use the exported logs to import the data into a mapping program to locate WiFi access points.
Used with most any mapping software that accepts generic NMEA serial data.
Interfaced to a microcontroller such as the Parallax Basic Stamp series or Bascom-AVR with the Atmel AVR chips, for various microcontroller & AVL projects.
Used with home made avionics computers for onboard flight recording and tracking systems for Model Rockets, Airplanes, Balloons and outdoor robotic systems.