NailO is a wearable input device in the form of a fingernail art sticker. It works as a miniaturized trackpad that can connect to your mobile devices; it also enables wearers to customize the device to fit the wearer’s personal style. NailO was created by Cindy Hsin-Liu Kao of the Living Mobile group and Artem Dementyev of the Responsive Environments group.

Press about NailO:
NailO turns your fingernail into a tiny trackpad (CNET)

Thumbnail track pad (MIT News)

This Adorable Thumbnail Trackpad Could Actually Be Useful (Wired)