SparkFun Breadboard Power Supply 5V/3.3V
Here is a very simple breadboard power supply kit that takes power from a DC wall wart and outputs a selectable 5V or 3.3V regulated voltage. The .1" headers are mounted on the bottom of the PCB for simple insertion into a breadboard. Pins labeled VCC and GND plug directly into the power lines. The lone pair of pins have no electrical connection but help support the PCB.