Before we do that, though, I want to get across one point about QRs—they cannot contain unlimited information. Each character you add into the code makes the code more complex. This isn't bad for the most part, but at some point, the code can become too complex for your device to read. For example, on Wikipedia's page about QR codes, they have 6 code samples. With your own QR reader, scan in the following samples (from left to right):
The point is this: before you start handing out really long web addresses or documents via QR, keep in mind that this technology is not just a magic bullet—you've got to plan out ahead of time how you're going to use them. The smartest habit to get into is just shortening all links, even if they'll naturally fit into the QR code—this way, you'll know that they're condensed into a format they'll easily be accessed.