What Colour Is It? OS X Screensaver
A Mac screensaver of this website: http://whatcolourisit.scn9a.org/
Download the latest release here!
Who's this by?
Original idea and website by J.E.Murphy
Screensaver by Jonic Linley
Anything else?
This was built on Yosemite and has been confirmed as working on El Capitan - no guarantees it will work on your Mac! If it doesn't, then there's the source code so you can fix it!
Also available as a Chrome Extension that shows this in new tabs