Locust has come up with a bootable linux cdrom that can turn any laptop into a wireless mesh networking accesspoint. The device acts as a wireless accesspoint, and is aware of other accesspoints in the area. From Wired:
In the future, each Wi-Fi system will also act like a small router, relaying to its nearest neighbors. Messages can hop peer-to-peer, leaping from lily to lily like frogs — the stems are not required. You have a broadband telecommunications system, built by the people, for the people. Carriers are aware of this, but they discount it because they do not feel there will be sufficient coverage. They are wrong.