Vibrating alerts are useful in situations when a loud ringer may be inappropriate or undesirable. Unfortunately, most phones have just one type of vibration alert. An Android app called Vybe - Custom Vibrations can help you create custom vibration alerts that you can use for different contacts. In doing so, it can help you identify callers, even if your phone is in your pocket.
Creating a custom vibration alert is easy to do in Vybe. You just tap the record button, create the vibration sequence you want, then save it. You can then assign contacts to use that particular alert.
You can also go back and view the custom vibration alerts you've saved and assign them to other contacts at your leisure. However, as Addictive Tips points out, there's no way to tell which alert has been set to which contact, and the alerts can't be named.
While Vybe isn't the only custom vibration alert app for Android, it does have an attractive UI and should be useful for those that rely on vibration alerts.