Mitch Wagner sez, "uGrokIt lets people attach RFID tags to their stuff, locate it with a device that attaches to a smartphone, just like in Cory's Makers." The Geiger counter-style audio cues are a nice touch, and I like the salaryman who uses the gizmo to remind him that he's left his phone-charger under one of those pointless stand-up cards next to the nearly pointless land-line phone in his hotel room.
(Thanks, Mitch!)