DIVE INTO FREE NETWORKS /
kismet
Mike Kershaw
http://www.kismetwireless.net
*nix
GPL
Kismet is a slightly more interesting wireless network 'sniffer'. Interesting because not only does it dish the dirt on anything it sees in the 2.4Ghz waveband (along with all the details you could ever want to know), it is Free Software, so you can do all kinds of interesting things to tie it in with other pieces of software (such as GPSdrive - a Free Software GPS utility) to create maps of wireless activity in your local area. Very tasty.