About a year ago when I first started with Arduino, I learned that projects can be taken off the arduino to stand alone on a breadboard or finished PCB. I also discovered that it was significantly cheaper and easier to buy an ATMega328 chip without a bootloader and burn the bootloader yourself instead of buying one with the bootloader preloaded.
I followed a guide from 3guys1laser.com to get everything I needed to burn a bootloader onto a breadboard:
I then decided that it would be inconvenient to have to bring out a breadboard and wire everything up every time I buy a new ATMega chip. Thus, I created a "shield" of sorts that would plug directly into an Arduino.
I used a ZIF socket to make taking ATMega chips in and out a breeze. And since I've been experimenting with photography and animation lately, here is an animation of the shield in operation, burning a bootloader onto an ATMega328:
I do not have any code or schematic for this project since it was all done on-the-fly (and before I knew about github and Fritzting!). See the guide at 3guys1laser for details on how to make your own!