Your phone to guess how old you are. ReconAge with the makers would be able to. The app tries using a photograph to guess your age. ReconAge look at your biometrics and make an estimate on that basis. You do need an internet connection to be able to get answers. The Android app is primarily meant to be funny and should lead to much laughter during an evening with friends.
The company behind the app says to use the same facial recognition software that uses the advertising industry to ensure that their ads will link to the right people. Good appreciation of all ages is not guaranteed, so the results you need with a little salt. If you are younger than fifteen years, the margin for error is greater.
ReconAge thought I was two years older than I am actually am, which is a reasonably good bet. The app is especially fun to use once at a party, but it seems the fun is really off. ReconAge is free to download in the Android Market. The minimum you need to Android 2.2 app to use.
Download the Market: ReconAge (free)