A pattern of pulses (haptic feedback) tells you the current time.

Tap, shake, or bump your phone to trigger the haptic clock to vibrate.

Works even with your screen off.

However, there are some phones for which it does NOT work with the screen off. Please star the bug #11028 at

http://code.google.com/p/android/issues/list

Please do not leave a negative rating here if the app doesn't work with your screen off. But, please DO use the feedback page on the website hapticlock.com, and include your phone and OS info.

Free version, limited functionality after trial period.