It really depends on what you want to spend and if there's anything else you want to control now or in the future!
Something as simple as http://www.automatedhome.co.uk/revie...r-devices.html would let you SMS control a device or two.
Or something based on Z-Wave, LightwaveRF or ZigBee technology would give you a much more flexible system allowing scheduling, monitoring, local and remote control.
Plenty of options really!