Comment on AirPort Radar

Love this widget. Simple, handy, and very quick scanning.
It's always running on my Mac, as I'm almost always moving around, looking for wireless access, and the signal in my dorm room is incredibly weak. This lets me zero in on the right spot.

Heck, on its own, this is practically a wardriving tool. It displays whether or not a network is password-protected without having to connect, so you can easily find an open one.