You can encode almost any sort of text into a QR code: a URL, phone number, text message, email address, twitter handle -- maybe even a haiku. QREncoder makes creating codes easy. Fire up the app, select the type of code you want, and bung your text in the box.
You've got a choice of size for your QR code, 5, 6, 9 and 12px and you can save it as a PNG for later use.
QREncoder is quick, easy to use and free from the Mac App Store, so is well worth checking out if you want to create quick response codes.