Super handy for creating any sort of presentation, website, or any other sort of visual design, I found this the other day: The Flickr Color Selector. For example, here’s an image that (kind of) matches the background of this website:

Grab Hold! by Jannes Pockele, under the Creative Commons 2.0 Attribution license.

Even though this doesn’t really match, with some deft Photoshoppery, I’m sure you can get some decent results. Make sure that the image is licensed properly for reuse and editing, and if you use the image on a public site, don’t be like certain multinational corporations, and make sure to ask the author first about it, even though you’re not obligated to legally.