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.

Instructables user ASCAS shows off how to add voice control to your Arduino projects using your Android phone and Bluetooth. The Arduino gets a Bluetooth attachment and a set of code.

To control the Arduino he’s using ArduDroid with a Bluetooth module. The app lets you trigger the various digital and analog outputs, and send and receive data.

This project incorporates communication between an Android Phone and the Arduino using Bluetooth. The basic functionality includes taking messages from an android phone, displaying them on an LCD ...

Arduino is a do-it-yourselfers dream that allows you to create a true smart home experience tailored to your needs. Check out how to use Arduino to build the smart home you want.

For now, it's only possible to connect to an Arduino board through USB via an OTG cable, but joaomcgd says he plans on adding support for Bluetooth or Wi-Fi receivers in the future.