A shift register will, in the end, let you expand on the digital outputs you have on your mictrocontroller. Each one of these 74HC595s can act like 8 more digital outputs, and you can daisy chain them. So you could hook 8 of them up next to each other and have control of 64 outputs. Simple shift register IC. Clock in data and latch it to free up IO pins on your micro.
Check out this tutorial on how to use this product with a 7 Segment LED and Arduino.