Someone posted a pretty interesting riddle game on my european guild's website:
http://www.ouverture-facile.com/riddles
Supposedly it has nearly 100 riddles, and you gotta keep solving each page to get to the next. Some riddles are quite challenging.
Here's the rules:
http://www.ouverture-facile.com/start/rules.html
The first 10 are fairly simple in what you gotta do to complete them, after that it gets more complicated.
Oh and.. NO SPOILERS!
/aed