The process of learning about the Arduino development platform is a fun one, and there's no doubt that blinking LEDs still hold a simple but fascinating attraction. However they're also useful for indicators when experimenting with other components - such as learning how to use shift registers to add more digital outputs to your Arduino or compatible board.
This process has been demonstrated by Andrew Ferguson who runs through using two 74HC595 shift registers and some example code to get sixteen digital outputs from only three digital pins on his Freetronics Eleven. Due to the nature of sending data to a shift register, it's ideal for counting in binary and demonstrated in the following video:
If you're looking to learn how to get more from your Arduino or compatible board, you can't go past "Arduino Workshop - A Hands-On Introduction with 65 Projects” by John Boxall.
Arduino Workshop takes the reader from having zero knowledge about the Arduino platform, electronics and programming and leaves them with the know-how and instructions on everything from blinking an LED, to robotics, wireless data, cellular communications, motor control, sensors, Internet connected systems and more. For more information including a sample chapter and table of contents, visit the book page.