Hello, i' ve developed an Android Application to control an Arduino board over Bluetooth. It can be used mostly for rc cars. Below you can see some screenshots:
This is the main Layout of my App
Here you can take a look at the main Menu
Lets start Searching for Bluetooth Devices
A new Device is found, click to connect
Please take a look at my app and let me know what you think of it 
You can get some more information here:
More Information
Here you can download my application:
Google Play
Follows a short Description
With this application we can handle any wireless #Bluetooth remote-controlled vehicle that uses the #Arduino platform or a similar one. We can perform basic steering functions like, left, right, front and back by using either the D-pad, yellow round buttons, or the accelerometer sensor of our device. There is a nice menu on top with some pretty good features.
Main Menu Features: Navigate to phone settings, Enable Bluetooth adapter, Disable Bluetooth adapter, Disconnect from a device, Make your device discoverable, Search for new Bluetooth devices, Get the list of paired devices, Application description, Minimize.
Extra Features: Change PWM, Three axis values, Enable/disable navigation using the accelerometer sensor, Yellow round buttons change color according to accelerometers orientation.
Please let me know if you like my app...