Button Remapper for Rooted Android Smartphone
While I was still using Windows Mobile smartphone earlier this year, AE Button Plus was one of the most needed software for me to customize all the hard / touch sensitive buttons. A similar software is now available for free, though it is only tested with Desire HD and will required your Android smartphone to have root access in order to change the button behavior.
The Button Remapper comes with a standard set of pre-defined functions, allows you to launch the camera, control the media player with a different button. Available in Beta version, the author is improving the software to support more devices. You can try the software and give your feed back here.