Apple Pencil • The Apple Pencil is a digital stylus pen that works as an input device for the iPad Pro tablet computer and was designed by Apple. It was announced alongside the iPad Pro and released in conjunction with it.
Matias Ergo Pro • The Matias Ergo Pro is an ergonomic keyboard with Matias' "Quiet Click" switches, staggered QWERTY layout, and two half-keyboards which can be individually adjusted.
NVIDIA SHIELD tablet K1 and its input stylus • The NVIDIA SHIELD tablet K1 is a high-performance tablet for gamers. Together with the SHIELD controller and GeForce NOW™ game-streaming service, this Android tablet is transformed into a powerful gaming system.
Steam Controller + Steam Link • Bring your existing collection of PC games with you to the living room. Simply connect Steam Link to your TV and home network and access your full library of games and the complete Steam catalog.
And the Wingnut for Best commercial alternative or other input device 2015, as voted for by the members of deskthority, goes to...