Freifunk.net (German for: "Free radio") is a non commercial open initiative to support free radio networks in the German region. Freifunk.net is part of the international movement for free and wireless radio networks.
To support the fast deployment of free radio networks, a specialized firmware for the WRT54G devices exists: the freifunk firmware. With this firmware, it is relatively easy to bring up new wireless mesh networks using ad-hoc communication and layer 3 routing with OLSR. More information can be found on the firmware's homepage.
Freifunk is built on top of the openWRT firmware.