Did you know your Arduino can burn bootloader into Atmega chips, turning them into Arduino compatible microcontrollers. It required a breadboard and a whole mess of jumper wires but we've just made it a ton easier on you with the AVR ISP Shield! 
It is very easy to use. Just following the Arduino tutorial, You can turn your Atmega chips to Arduino compatible microcontrollers or change the bootloader of the Arduino boards. Such as you can turn the Crowduino to a Arduino UNO board.