I think this is a very striking image:
Copyright © 2008 – Mirko Ilic Corp All Rights Reserved. Reprinted by Permission.
As I work on a blog redesign, it's one of my favorites for a theme. But unfortunately, both its verticality and its greenness make it hard to use; it looks like I'll end up with something a bit less striking, more soothing, and much more horizontal, as a banner.
The artist — whose work came to my attention because of this great image regarding court decisions supporting gay rights — very kindly gave me license to use it if I wanted to.