I did a cover for my own copy (still haven't read it yet, but i will as soon as I have time). Feel free to do what you will with it, and if you want the original document it was done in the Gimp (.xcf) but I can translate it to Photoshop (.psd) if you need it.
As ever, if you want anything changing on the cover, have a different idea of how it should be, or what have you, give me a shout and I'll see what I can do.