Wardriving is the act of searching for Wi-Fi wireless networks by a person in a moving vehicle, using a portable computer or PDA.
Software for wardriving is freely available on the Internet, notably NetStumbler for Windows, Kismet or SWScanner for Linux, FreeBSD, NetBSD, OpenBSD, DragonFly BSD, and Solaris, and KisMac for Macintosh. There are also homebrew wardriving applications for handheld game consoles that support Wi-fi, such as sniff_jazzbox/wardive for the Nintendo DS, Road Dog for the Sony PSP and Stumbler for the iPhone. There also exists a mode within Metal Gear Solid: Portable Ops for the Sony PSP (wherein the player is able to find new comrades by searching for wireless access points) which can be used to wardrive.
A map of Seattle's Wi-Fi nodes, generated from information logged by wardriving students in 2004.
In December 2004, a class of 100 undergraduates worked to map the city of Seattle, Washington over several weeks. They found 5,225 access points; 44% were secured with WEP encryption, 52% were open, and 3% were pay-for-access. They noticed trends in the frequency and security of the networks depending on location. Many of the open networks were clearly intended to be used by the general public, with network names like "Open to share, no porn please" or "Free access, be nice." The information was collected into high-resolution maps, which were published online
Congrats to whitedice, who managed to accumulate a million located new-to-WiGLE networks.. *by himself*! I, for one, welcome our new cyborg nethugging overlord.-bobzilla