What's the best technology to use to track people who like to wander off? You might be inclined to say GPS, but stagger into a cave or basement (or, sometimes, a city street) and suddenly you're off the grid, man. Not with Ekahau's T301W wristband: it uses Wi-Fi to beam location information. Yes, we know that your average cave doesn't have Wi-Fi, but Ekahau has a range of beacons available that will fix that, and when in the presence of those beacons (or any other configured Wi-Fi network) a wristband can be located to within a few feet. It's the latest of a variety of similar devices from Ekahau, but the first small enough and waterproof enough to be wearable, which has the company envisioning everyone from cruise ship captains to secret service agents slapping these on their visitors. At $60 a pop, though, we're not sure how many organizations will be able to afford that many.