Warning : These may be quite addictive and would require you to consume lot of brainpower :)
Da Vinci's Other Code - http://www.coudal.com/davinci.php School of Government - http://www.coudal.com/theotherfish.php Einstein's Fish Puzzle - http://www.coudal.com/thefish.php
AND
Which Porn Star Ate the Most Hot Dogs? - http://www.coudal.com/hotdog.php
(via Coudal Partners)