Test+Your+Knowledge

(If you find another site, add it to the list) 

http://www.flashbynight.com/test/ - This is a smart test.

http://www.allthetests.com/tests/smart.php3 - This is another smart test.

http://www.coolmath-games.com/iqgame/index.html - This is an IQ game.

http://letterbox.lexigame.com/ - The letterbox game.