This picture was taken using long exposure photography with a staff that lights up according to how strong the Wi-Fi signal is. Check it out! There's even a video below:

Designed by Timo Arnall, Jørn Knutsen, and Einar Sneve Martinussen, the 12 foot rod has 80 LED lights that pulse high and low given the strength of the network. They combined this with long exposure photography. 
The strength, consistency and reach of the network says something about the built environment where it is set up, as well as reflecting the size and status of the host. Small, domestic networks in old apartment buildings flow into the streets in different ways than the networks of large institutions. Dense residential areas have more, but shorter range networks than parks and campuses.
[Flickr and YOUrban via Designboom]