Chances are, you're used to working with smartphones using nothing but the touchscreen display. And it's great. But if you've ever wished you can have physical buttons for triggering certain functions on your device, you might want to take a look at Dimple.
An NFC sticker with multiple buttons, you simply stick it on the back of your phone (so it gets in close proximity to the NFC antenna), then use the accompanying app to assign functions to each one. Whether for launching specific apps, turning on the camera's flash (instant flashlight), or quickly calling a contact, it gives users a shortcut to different actions that is much quicker than going through the standard UI. Heck, you can even use it to run Tasker tasks to get multiple things done in one push.
Dimple comes in two variants: Mini (two buttons) and Standard (four buttons). The buttons are lined along a small Band Aid-like sticker that, while not exactly pretty, shouldn't really ruin the phone's aesthetic all that much. It only works with Android phones and tablets that have NFC (obviously), with the exception of those with metal bodies like the HTC One (whose antenna location, apparently, doesn't play nice with the sticker). The sticker is waterproof and require no power source. Oh yeah, the screen needs to be switched on in order for the buttons to work, although screen-off triggering is possible for rooted devices (you'll need to install Xposed framework).
An Indiegogo campaign is currently running for Dimple. Pledges to reserve a unit starts at $17.