You can create a QR code for any bitcoin address using Google's QR code maker:
Just point to that as the img src and you'll get something that looks like this:
Note this address is used by a lot of tests as the private key is literally "1".
Btcwidget.com allows you to create custom widgets like this with your address.
Here is a great browser extention that finds a bitcoin address anywhere on the page including in the head. It can track your browsing time on each website with a btc address and then you can designate tip amounts to be paid to that site every certain period of time by your history. http://protip.is/