If you want to be able to control it from your Android device, you can use a ODControl (we produce it in the company where I work in) and create a desktop icon. It will work just as a real app where you can switch on and off up to 8 devices (heating system, lights, etc). It has an Ethernet interface and a webserver, so you will need to configure your router to allow access from Internet (check DynDNS for that as well).
EDIT: All the material you need is:
- ODControl (the controller itself)
- 12V relay to open and close the circuit
- 12V CC power source, minimum 500mA
The controller has an Ethernet interface and web server embedded, so you can just connect it to the local network and access it via WiFi, or from Internet (after configuring your router properly).
But if you really want to have an Android App, in the opensource community (in Spanish) website there are several Android Apps being developed, and you can test them as well.