How to make the Backspace key to take me to the previous page in Safari 6?
I actually asked a similar question (but more broad so this isn't a duplicate). I got this as an answer (it works, I tested it):

Write the below line in terminal:


  defaults write com.apple.Safari com.apple.Safari.ContentPageGroupIdentifier.WebKit2BackspaceKeyNavigationEnabled -bool YES


Then restart Safari.

Hope this helps!