For a less nifty, but probably also less complex solution, I'm using Ciseco radio units to build some home automation at the moment. They're available for < $20

For a less nifty, but probably also less complex solution, I'm using Ciseco radio units to build some home automation at the moment. They're available for < $20, and with the right aerial have a range measured in kilometres (although more usually a few hundred metres). I'm pretty sure there's also a repeater mode on the actual radio modules if you need extra range.