WiFi can be organized according to peer to peer principles as Mesh Networks.
See also our entry on Wireless Mesh Networks
You can have a "Wi-Fi network that is not top-down but rather ground-level, peer-to-peer. It relies not on $3,500 radio transmitters perched on street lamps by professional installers but instead on $50 boxes that serve, depending upon population density, more than one household and can be installed by anyone with the ease of plugging in a toaster.
Meraki Networks, a 15-employee start-up in Mountain View, Calif., has been field-testing Wi-Fi boxes that offer the prospect of providing an extremely inexpensive solution to the “last 10 yards” problem. It does so with a radical inversion: rather than starting from outside the house and trying to send signals in, Meraki starts from the inside and sends signals out, to the neighbors.
Some of those neighbors will also have Meraki boxes that serve as repeaters, relaying the signal still farther to more neighbors. The company equips its boxes with software that maintains a “mesh network,” which dynamically reroutes signals as boxes are added or unplugged, and as environmental conditions that affect network performance fluctuate moment to moment." (http://www.nytimes.com/2007/02/04/business/yourmoney/04digi.html?)
Details about the Meraki Mesh Networks