A Mod by Matt on the XDA-Forums allows anyone to turn one of the volume buttons into a camera button.  Which ever volume button you assign will still function as usual until you get to the actual Camera app when you want to take a shot. Volume2Camera Mod “This mod means you can now snap photos using your volume buttons. Works on all De-odexed Sense ROMs, including Android Revolution, TrickDroid and Renovate. (NOT STOCK ROM) Latest 2.24 base Camera apk

 Many thanks to Devs like Matt who make our lives better.

http://forum.xda-developers.com/showthread.php?t=2332252 HTC One camera button mod volume