I’m a big fan of the PowerSwitch Tail. It’s an awesome power cord equipped with a relay board that enables a relative neophyte maker (say, can run the Blink sketch in Arduino) to safely control high-voltage electrical sources. It’s great because it’s pretty much foolproof and as safe as any extension cord.
Ryan Edwards of Sparky’s Widgets shot this YouTube video showing how to build a DIY version of the PowerSwitch Tail that can switch up to 120VAC/12A.
Ryan reports that the total cost is under $20, which doesn’t compete much against the $27 PowerSwitch Tail (available at the the Maker Shed) but it’s always cooler to make one yourself!