MacWireless WiFinder

[seraph]

This handy little device will allow you to easily find and zero-in on an access point with the click of a button. Keep it on your keychain and easily locate hotspots without even booting up a laptop. Unlike many wireless network locators, the WiFinder is capable of distinguishing between a wireless network and other devices on the same frequency, such as a cordless phone or a microwave oven. Point the WiFinder in one direction and four LEDs display the strength of wireless network signals in that direction.

http://www.macwireless.com/html/products/accessories/wifinder.html