I create a project with android and arduino for control my coffee maker from my android smartphone or tablet.For communication between android and arduino i use bluetooth connection.The coffee maker communicate with arduino directly with relays.
My android application is there https://play.google.com/store/apps/details?id=coffee.maker.remote
The arduino side is very easy.I use serial for receive and decode the bluetooth signals and send commands to digital pins for drive the outputs for relays.If connect and ethernet card or gsm shield or old cellphone as modem we can make coffee from a web browser or with sms.