Freifunk
From 25C3 Public Wiki
[edit] Freifunk
"Freifunk" is a non-commercial initiative for free wireless networks. These free Wireless Networks will build up and adiministrated by citicens at there own. Every member has to give access to his own accesspoint to transfer data to other members. So it is possible to transfer data (web, text, music, films,..) over this network but also you can f.i. use chatserver or something to communicate with other people.
see more at Wireless