MacStumbler 0.7 beta

MacStumbler is a small utility to emulate the functionality of projects like netstumbler, bsd-airtools, and kismet.

It's meant purely for educational or auditing purposes, although many people enjoy using these types of programs to check out how many WiFi (wireless) networks are in their area, usually known as "war driving".
MacStumbler only works with AirPort wireless cards, it does not (yet) work with any PCMCIA or USB wireless devices.
To enhance the scanning results, many wardrivers like to use external antennas to increase the range. The new iBooks and Titanium PowerBooks both contain an antenna built into the screen (which can provide much better range than standard PCMCIA cards by themselves). This built-in antenna is directional, I find my iBook gets the best signal when the screen is facing away from the access point.