This popular wireless stumbler for Mac OS X offers many of the features of its namesake Kismet, though the codebase is entirely different. Unlike console-based Kismet, KisMAC offers a pretty GUI and was around before Kismet was ported to OS X. It also offers mapping, Pcap-format import and logging, and even some decryption and deauthentication attacks.
For downloads and more information,
visit the KisMAC homepage.