One of the places where the obsessive design and engineering that went into the iPhone becomes obvious is its home button. It certainly is not perfect, as many people prefer to have an additional back button, but it does have a big advantage: since it is a 'hard' button (as opposed to 'soft' touch buttons) and slightly recessed, it gives you physical feedback when pressed without being easy to activate accidentally.
Why does that matter? By combining those two properties, it can be used to turn on the screen on Apple's iOS devices, instead of reaching for the power button. While many Android devices also come with hard buttons, they can't be used to turn on the screen by default – and even though you can change that using various mods, they may activate accidentally. Newer Android devices, on the other hand, often include capacitive buttons that naturally aren't suited for this kind of usage. However, that does not mean that you're stuck with the power button for good, thanks to a mod for the HTC EVO 3D that allows you to turn it on and off with a simple swipe!
With the mod, you can set a custom swipe gesture to turn on the screen, and another to turn it off again. You do that by defining the start and end point, respectively – for example, if you set the top left corner as the start point, and bottom right corner as the end point, you'd have to swipe all the way from top left to bottom left. There's another option to use pre-defined "left to right" or "right to left" gestures, which, as an added bonus, even work on the touch area of the capacitive buttons.
Since the mod is in fact a kernel module, it is device-specific and only compatible with the HTC EVO 3D. But good news: you do not actually need to flash anything, as all the sophisticated action is hidden in a simple to use application called PGM - Ponury Gesture Mod that can be downloaded from the Android Market. Being such a low-level hack, you'll still need root access, though.