Three Norwegians have built a WiFi measuring rod in order to "visualize the immaterial networks found within cities". As they move around with the 4 metre rod, the 80 LEDs that run its length pulsate based on the strength of a selected WiFi signal. Through time-lapse photography, the pulsing lights create a physical representation of how different types of networks behave in their specific environments. See more photos on the designboom website, as well as more details on the people and the philosophy behind this.