Notpron, the hardest riddle on the net. I don't know if any of you out there in cyber-land have ever heard of this site but its pretty sick. You go from page to page decivering different riddles. The pages go up to a hundred and thirty nine, and of the 10,000,000+ people that have tried it only 114 have succeeded in finishing it. The riddles are as varied as rewriting the web address backwards, to using morse code to attain the password, and not one riddle is repeated, ever. I just got put on to it and I am right now in stage 13 (or room 13 whatever you like), looking back I can't believe how far I've come. This is one of those things that forces you to think- how do people come up with this stuff?
Check it out here
Really, you'd be amazed how proud you get when you deciver a riddle all by yourself and without having to resort to cheating.