Play Bad Apple
Minesweeper type game. Very colourful and quite difficult too!
Play Brain Train
Play Dr. Kawashima's Brain Training: Brain Age Check! This is a free demo version of one of the Nintendo DS Brain Train games. This Flash version is about math. Example: 2 + _ = 9.
Play The Ultimate Idiot Test
How smart are you? More importantly, how dumb are your friends? Take the super-scientific Idiot Test and find out once and for all! Remember, the Idiot Test was put together by people much smarter than you.