The Serval project is a mobile free global mesh network being headed by Dr Paul Gardner-Stephen and a team of engineers and developers. They have already released an Android app, very interesting http://www.servalproject.org/
Providing local information during an “internet kill switch”.
Due to recent events in Egypt and the speed of the shutdown.
Most of these projects are open to contribution and further development.
B.A.T.M.A.N – http://www.open-mesh.org/
Roofnet | http://en.wikipedia.org/wiki/Roofnet
GNUnet | https://gnunet.org/
Netsukuku | http://en.wikipedia.org/wiki/Netsukuku
Open Mesh Project | http://www.openmeshproject.org/
OLPC Mesh Network | http://wiki.laptop.org/go/Mesh_Network_Details
Open source BGP | http://en.wikipedia.org/wiki/Border_Gateway_Protocol
sMesh | http://www.smesh.org/
Coova | http://coova.org/
SolarMESH | http://owl.eng.mcmaster.ca/~todd/SolarMESH/
WINGproject | http://www.wing-project.org/
Wiki list of mesh protocols: Wikimedia list of ad-hoc mesh protocols and packet routing
Even bigger list of ad-hoc routing protocols: http://en.wikipedia.org/wiki/Ad_hoc_routing_protocol_list
Basic explanation – how this stuff works:
Example of a working grassroots wireless community
The list here is to consolidate information, please feel free leave any protocols that have been left out and relevant comparison/analysis of mesh solutions in the comments.