PingWallet is a new smart startup that aims to find your lost credit cards at any place.
How It Works:
Ping connects to your iPhone and Android smart phones using Bluetooth 4.0, and sends an alert reminding you to return your card back to wallet after each use or if a card has been removed unbeknownst to you.
It also allow you to open a tab at a bar or restaurant using the Ping app. After a certain amount of time, the Ping app will remind you that your card has not been returned to your wallet.
Ping can be located using proximity searches or sounds in the event the wallet is lost, stolen or accidentally left behind. Ping* helps make losing or getting your wallet and/or cards stolen a thing of the past.
More at: http://pingwallet.com/