Lifehacker Australia usefully reports that "Multicolr Search Lab Sorts Flickr Pictures by Colour.
Need an image with dark blue and green undertones for desktop wallpaper or a design project? Multicolr Search Lab, a free search utility, digs through roughly 3 million images in Flickr's 'Interesting' set for photos featuring the colours you select. You can make one colour more prominent by selecting it multiple times, and the results seem pretty genuine—though you have to find the colours with your eyes, and can't put in hexadecimal or RGB values grabbed from graphics programs. The colour search engine also has a front end for Alamy Stock Photography for those in need of definite royalty-free images."
