Source: http://lifehacker.com/5512349/create-instant-qr-codes-with-a-bookmarklet
Creating camera-phone-friendly QR codes with a goo.gl shortlink URL tweak is nice, but one of our readers took the next logical step. His bookmarklets creates a goo.gl link, automatically converts it to a QR code, and shows you the result.
Hosted at his public Dropbox, reader grewal12 put his JavaScript skills to work, offering up two different versions of a bookmarklet. You'll need to copy the code and save it as a new bookmark manually, but once you do, it's a handy little thing. Go to a page you want to make easy for Android and iPhone users to get to with their camera scanners, hit the bookmarklet, and, depending on which version you picked, your code will appear in either a tiny new window or in the same browser tab. Handy stuff.