I find QR codes to be extremely useful in class for quick reference items. We have used them when we create a research bulletin board/poster, as a quick way of citing references for student work, a board for accessing commonly used websites and current assignments and rubrics. For all this to run smoothly, you need a good way to create QR codes for the content necessary.
I use two different tools:
When working outside a chrome browser, I use goqr.me. It is a versatile creator and allows you to load a number of different types of content into your QR code – like phone numbers, instructions, geolocations, even WIFI instructions. It is easy to use, and creates codes quickly. (Thanks to Susan Watt for showing me this one)
The second is a browser extension for Chrome. ShortenMe is a button for the browser that, when clicked, creates both a goo.gl link, and a QR code. I sue this as a quick and easy method of adding QR codes, and shortened URLs to anything I am creating. This is especially useful when using google docs, as the URLs end up being quite unweildly.