Just joined this awesome site - http://www.colourlovers.com/ I love colors so I'm probably biased. But thought it might be a cool resource for anyone tinkering with their self-published book cover. They have awesome color palettes and great patterns. Forgot to add they have a generator on the site to allow you to color patterns anyway you like. Good for backdrops or color coordinating, or whatnot. All free I think, and they welcome you to use them as long as you're not selling the prints. Just make sure you read the specifics for each color palette. Most just want name credit.