I've just done a tutorial on my blog explaining how to add canvas to your image and fill it with the original detail from the photo - meaning you don't have to waste time messing about with the clone stamp tool. I expect a lot of people will already know about using this technique but for those that do not...

Quick and easy canvas extension.

I used the below image for the step by step tutorial, showing how I gave the duck more space to swim in to in less than 30 seconds, whilst preserving the texture in the water.



Hope some of you find it useful :)