Someone selects a coin and holds it in their closed hand. You use your iPhone as a metal detector and scan their hand.
Your iPhone correctly guesses the coin!

iTunes Review:Rating 5
"This app is really cool for tricking people. Good graphics"

Promodispenser.com
"After reading the instructions, I enjoyed toying with my wife. She is still trying to figure out how it works. …for an occasional party trick it's a good choice."  

Promodispenser.com
"Its great haha, i didnt think it would actualy work but it did. Wow it's awsome and so cool so gona show it off to friends :)"