Simple shift register IC. Clock in data and latch it to free up IO pins on your micro.
Check out this [tutorial](http://cdn.sparkfun.com/datasheets/Components/General IC/arduino_segment_led.zip) on how to use this product with the [7 Segment LED](http://www.sparkfun.com/commerce/product_info.php?products_id=9191) and Arduino. Thanks Patrick and Mycha!
* [Shift Register Tutorial](https://learn.sparkfun.com/tutorials/shift-registers)
* [bildr blog - 74HC595 ](http://bildr.org/2011/02/74hc595/)
* [7-Segment Library](https://github.com/Qtechknow/Arduino-Libraries/tree/master/Pineapple) (Thanks Quin!)