Back in 2010, Smashing Magazine published a good/popular blog with a Drupal cheat sheet background image.  Fast forward three years to current year of 2013 and we need an updated version for Drupal 8.  This should be a fairly simple task by going to api.drupal.org, finding each function in Drupal 7, then finding it in Drupal 8. Then of course turning it into a Desktop image.  

http://www.smashingmagazine.com/2010/06/14/drupal-cheat-sheet-wallpaper/

NOTE #1: If unfamiliar with Smashing Magazine...go read it. 

NOTE #2: We're not too worried about a fancy desktop image to complete task. We're more worried about an updated cheat sheet!