According to the latest HTC One Max leaks, the fingerprint scanner located on the back of the device may be used for more than just security purposes.
The leak, which comes via HTCSource, indicates HTC plans to use your fingerprints to launch apps. The launching of an app would be tied to a specific finger, with the capability of scanning and storing up to ten fingerprints.
In addition to unlocking the device, and launching specific apps based on the finger you scan, you can also swipe in various directions and combinations to carry out different tasks on the device.
Again, this is all rumor and speculation from leaked documents, but it looks promising (if not down right fun).