Amnesya.com
A bunch of intertwined riddles that have to be solved in order to get to the next one. Over 90,000 people have tried it. None have finished it. Right now, I'm stuck on level 8. Now don't tell me this goes into wibbles, because in order to figure this out, you have to think outside of the box. This is amazingly hard. Trust me, if you don't believe me try to get past the mobile phone level. BTW, you need photoshop and some other programs to solve these riddles.
You may give hints on this thread.... But please, do not post the URL of any level! THAT'S CHEATING! Enjoy.
All of the neccesary programs are found on the homepage of this site