Ever been scared to venture into the world of controlling AC power from your microcontroller? Me too. And that’s smart, because household AC can hurt/maim/kill if you’re not careful. The PowerSwitch Tail is a safe, easy-to-use AC relay that is triggered with a mild-mannered 5V DC signal from your Arduino or other microcontroller or circuit. Computers can talk to Arduinos directly, but adding XBee radios to the mix makes your serial communications wireless.
Blendophone: iPhone + Arduino + XBee + Blenders
This project shows how to control big, scary 120V AC-powered devices using wireless serial communication and Arduinos. Specifically, I'll use a set of blenders as "musical" instruments controlled by a tilting iPhone.