This Bluetooth module ties directly into the Tx and Rx lines of the Arduino so a wireless serial connection between an Android device can be established.

Arduino 101* includes on-board Bluetooth® LE to enable developers to interact with Bluetooth®-enabled devices such as phones and tablets.

The watch is built around an Arduino Pro Mini, a scavenged Nokia LCD, and a BlueSMiRF Gold. The Bluetooth connects to a Nokia N900 with a little Bluetooth client app [Ahmet] wrote.

All you have to do to create a basic Internet of Things device is snap in some plug-and-play modules, connect your creation to your PC and draw connections between those modules in an editor.

Makers, developers and hobbyists that are looking for a low-cost Bluetooth Arduino compatible micro controller that can be controlled and programmed ...

Primo will include Bluetooth LE (low energy), NFC, Wi-Fi, and infrared built-in — you typically need a “shield” add-on to get these features.

The $22 kit includes an Arduino-BLE board and 6-pin header that should be fairly broadly applicable for building Arduino-based hardware that can communicate with iOS devices.

Joe Desbonnet combined an Arduino microcontroller with a magnetic coil to create what he calls the “Poor Man’s NFC”.