There was a thread which showed an interest in filters a little while ago. I thought I would share how I do graduated ND8 filters in PSP when I havn't taken or havn't bothered to to fit one on the camera. There seems to be so few tutorials on PSP I hope this is of use. This way works if you are using it to add dramatic interest to the sky, and the highlights are not burned out too much. Here are the before and after images.

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html