#31 Cheryl's Birthday Problem

There is actually more then one correct answer. But the most common answer is July 16th. Here you can find a very neat explanation of the other possible answers:

#30 Four balls riddle

You have to form a pyramid

Todays Riddle

If you have me, you want to share me. If you share me, you haven't got me. What am I? 

The answer is "a secret".

Illusion: Optical Color Illusion

Check out this awesome illusion. Just stare at the picture for 20 seconds and be amazed!

#29 Bridge Problems

Actually, there is no solution for this problem. It's only an april fool :) Check out this wiki article if you want to know, why there is no solution.