I have this relay handy http://www.sainsmart.com/sainsmart-4-channel-12-v-usb-relay-board-module-controller-for-automation-robotics.html
From what I gather, the raspberry pi should be able to use it, however I have no idea how.
I have another more suited one but I have this one lying around and thought maybe it would come to handy since it's usb one.
