swan song, it's (one of) the answer(s) to all of our microcontroller problems!
Sigma, after looking at the relay boards and shields, the one I bought isn't really a shield but just a board. Because cheaper and you're not constrained to the Arduino Uno

Hehehe, ozzie is right! They're sparkfun components, a 5V Arduino Pro Mini with an FTDI Serial to USB converter. Yup, the relays are pretty heavy duty for this application.