When you're swimming in the ocean, even the lowliest tissue becomes a water detector: Lo, a few years ago, when we were lonely islands of Wi-Fi connectivity in an uncaring void of wired broadband, cruelly locked away within homes and businesses, a Wi-Fi detector acted like a beacon, a lighthouse if you will, giving us some hope for a seamless tomorrow. Early Wi-Fi detectors lit up in some fashion, often using multiple lights to indicate a range of signal strength, when Wi-Fi was near. Later detectors added directionality, and then LCDs to show network names.
Now, drowning in the Wi-Fi surf, as it chops about our head and shoulders, the undertow sucking us deep, deep, deep linked down, full fathom 101--that's binary, folks--thy father lies, of his cables are coral made, those are radios that were his eyes, and so on, a Wi-Fi detector doesn't tell us more about the deeps. A solid, unblinking light, like the all-seeing eye of Sauron (cf., Lord of the Rings) just lets us know we're within the scope of Wi-Fi, not whether it's open, free, available, or, as is more likely, shut to the likes of us.
The pen is mightier than the sword, but you can't use a sword to determine whether a Wi-Fi network is around. Unless you threaten the nearest geek with it, I suppose. For $18.95, a nice, limited edition paperweight which, in most areas, confirms what we already know. Such as, my window is a rain detector--I open it up, lean out, and if I get wet, it's raining. [link via BoingBoing]