Found this by accident just today:
http://www.timtang.com/ttt/
I'm going to give it a go myself; thought it might be of interest to some of you who like a good challenge...
Click on the blue "only 114" link on the main page to see a list of peolple who have made it past the halfway mark of the test. No one has made it that far since May 2011 and, so far, no one has completed the test...