Based on a Nordic Semiconductor 32-bit ARM system-on-chip that has built-in support for Bluetooth 4.0, the RFduino runs the same code as Arduino UNO ... proximity-switch devices such as alarms ...

This remote switch uses a sg90 servo, an Arduino Uno, and pairs of ATtiny85s with HC-05 Bluetooth modules assembled on protoboards. The 3D printed mount screws easily on top of a standard light ...

The Switcheroo is small enough to fit just about anywhere The first tool is the Switcheroo, a tiny Bluetooth circuit ... their own [NFC reader] with an Arduino and 3rd party reader device ...