Kanex company released a keyboard with support for up to 4 devices simultaneously. The device has a USB-interface for computer and a Bluetooth-enabled 3 devices (eg, laptop, tablet and smartphone) at the same time, and switching between systems is tied to the buttons F1-F4. At $ 70, Multi-Sync has one important feature is that it only supports the operating system from Apple.
Read another very interesting article about alternative energy of the Sun, water and air.