Shows how to turn on multiple LEDs (32 could be done in this example) using the 74HC595 shift register (x 4).
Circuit and discussion here:
This example shows all 32 LEDs connected to the outputs of the 4 shift registers (8 bits per register, so you get 32 LEDs in all). Those are 1K resistors in series with each LED.
Some discussion on the Arduino forum about this project: