But if you want an address QR code to send some coin you can use the one on blockchain info.
Its just simpler and faster to hover the mouse over the address and have the QR pop up instantly.
My motivation and the final catalyst to implement this was when I wanted to make a few bets on bitbet.us (browsing it with my desktop browser) and my pocket-change money for such purposes being on my android phone. My other money is on a separate Linux laptop but I don't use that very often. They [bitbet] display the address as a clickable bitcoin:1xxxxxx link but they don't display the QR-code. So it would work if I had a wallet installed on that computer but I haven't. Instead what I wanted was to be able to hold my phone against the monitor and scan the address *WITHOUT* doing any additional steps of copy-pasting addresses from one website into another or using qrencode on the command line. Its just convenience. The same sort of convenience that made the invertor of the www invent the clickable hyperlink instead of copying or typing addresses into the address bar.
This greasemonkey script works as follows: After page load it will install a mousemove handler to the body of the document and then when you move the mouse over the website it will permanently try to match the word under the mouse pointer against a regular expression to determine whether that looks like a BTC address. If it looks like an address it will send it to chart.googleapis.com to generate a QR code image and display that. Basically it will do automatcally what you were doing manually.
