Multicolr Search Lab (from idee) has a tool that's a must for bloggers, or anyone else who wants to get photos with a specific color scheme. Simply select the colors you want (up to 10) and the tool will automatically return images from Flickr that match (see example below.) The list updates as you click and choose/remove colors.

The images are from Multicolr's library selection of 10 million of the most "interesting" images on Flickr. They come from Creative Commons, so you can feel safe in using the images for your website or blog. By clicking on the image, you are taken to the image on Flickr. You can also search by color with Alamyh Stock Photos, using about 3 million images.