Source: http://lifehacker.com/5511793/make-qr-codes-in-a-jiffy-with-googl
We recently highlighted how to make your personal QR code, but for those of you who don't recall, a QR ("quick response") code is a square barcode that makes getting URLs, location coordinates, any text or contact information onto a phone fast. With a barcode scanner app installed, you just point your phone's camera at the code to read its contents.
Gina detailed how to create QR codes using code generators like this or this, but if you're already using Goo.gl to shorten your URLs, simply add .qr to the end of a shortened Goo.gl URL and it'll instantly generate a QR code for you.
Once you've got your shortened Goo.gl URL—like http://goo.gl/3p8r, which points to Lifehacker's home page—just append .qr like so:
...and you've got your personal QR code. Not bad.
Note: To use Goo.gl to shorten URLs, you need to be using the Google Toolbar, or you can point your browser here or try this bookmarklet. Also, the other generators listed above offer QR codes that embed text, phone numbers, maps, and ready-to-send text messages in addition to URLs, so if you want more than just a shortened URL, they're probably better options.