It's not the same thing by any means, but I'd imagine you could bounce the cell signal off something, and capture the echo, or "listen" to its interference of surrounding background noise.
(for non-clickers: Sneakier Uses for Everyday Things: calculator + radio = metal detector)
http://books.google.com/books?id=91B7QvCX_iAC&lpg=PP1...
It's not the same thing by any means, but I'd imagine you could bounce the cell signal off something, and capture the echo, or "listen" to its interference of surrounding background noise.
(for non-clickers: Sneakier Uses for Everyday Things: calculator + radio = metal detector)