zMooth lets you use gestures to mimic your device's hardware keys (back, home, menu and power), you will be able to use very intuitive gestures to navigate your device.
zMooth is unobtrusive and uses minimum amount of screen space but very easy and intuitive to use. If you use for couple of days you won't even think about using the buttons.
After you install the app you will see a blue area at the bottom of the screen, swipe left on this area to go back, swipe right for menu, gesture a up-arrow(^) for home and gesture a lightning strike/thunderbolt to power off. Please check the screen shots and video for more info.
zMooth will also save your hardware keys from being prematurely degrading as you will be using them a lot less. It might also slightly increase your battery life as you won't be turning on button lights and triggering hardware button circuits.
Please try Lite version which is free before purchasing this app.