KisMAC - Free Sniffer/Scanner application for Mac OS X

KisMAC is an open-source and free sniffer/scanner application for Mac OS X. It has an advantage over MacStumbler / iStumbler / NetStumbler in that it uses monitor mode and passive scanning. KisMAC supports many third party USB devices: Intersil Prism2, Ralink rt2570, rt73, and Realtek rtl8187...