Adafruit Industries1430Development Kits and Tools

From the Manufacturer:

Put on your sunglasses before putting this shield onto your 'duino - 40 eye-blistering RGB LEDs adorn the NeoPixel shield for a blast of configurable color. Arranged in a 5x8 matrix, each pixel is individually addressable. Only one pin (Digital #6) is required to control all the LEDs. You can cut a trace and use nearly any other pin if you need some customization. 

To make it easy to start, the LEDs are powered from the 5v onboard Arduino supply. As long as you aren't lighting up all the pixels full power white that should be fine. You can also solder in the included terminal block (pro-tip: put it on the bottom of the board so it doesn't stick up) to attach an external 4-6VDC power supply. There's a polarity protection FET on there in case you wire the power backwards (we would never do that, it was, umm, a friend of ours, yeah that's it