French developer Marc Teyssier developed a robotic finger that plugs into the USB port of your phone. "MobiLimb" can crawl across a desk, wave when notifications arrive, receive finger gesture messages, or "stroke the user's hand." Marc built a Unity application to rapidly prototype gestures on Android, and he notes that reactions have been interesting. You can check the finger out in the video here, which is technically safe for work. He told the BBC people generally found the finger creepy or weird because it was so unusual, but hoped it would be "accepted" in time.