QR codes has changed the way we share URLs via print/screen media. Majority of brand advertisements you would be seeing in daily newspaper have this code. Really, it ease the task of sharing documents with people.
Like television screens, QR code has also the history of black & white appearance in its beginning days. Now, not even colorful codes can be made, but they can be embedded with colorful background and contrasting foreground images, such as your own photograph.
An online QR generator website qrhacker.com has come up with some cool customizing features such as adding background and foreground pictures, changing pixel colors and roundness depth. The interface is very user friendly that didn't appealed me to write about.
QR Code made with my own foreground image
Make a good contrast between colors to help scanner for easy code detection. There is a level indicator on bottom to alert you if you do over customization that makes the image undetectable.
After designing your code, you may order them for getting it printed on T-shirts, Mug or business cards.