You can't find your keys, your wallet or anything else. There are devices that can help you locate your lost items.
Consumer Reports tested the Stick and Find, the Cobra Tag and the BiKN that allow you to tag your stuff and find it when it's lost using your smartphone. All three devices have limited ranges. You have to be within about 30 feet for them to be effective.
The least expensive $25 Stick and Find sometimes took up to two minutes to find a signal. That's frustrating when you are in a rush to find something. The BiKN was quicker but it costs $100 and at the moment is only available for the iPhone 4 and 4S.
The Cobra Tag is just as quick but works with more devices and at $40 isn't as tough on your wallet. The Cobra Tag can work in reverse, too. So if you've lost your cell phone but still have your tagged keys, press the tag and as long as your phone is on the tag will ring the phone.