How many leds (with drivers...) can i use ?

Yes, have already seen that. And it doesnt answer my question. There is a max of 40 mA per I/O but... is that possible to give enough power to hundreds of leds and control them with the board :

http://www.arduino.cc/en/Tutorial/LEDDriver -> here 8 led = 20 mA * 8

I understand something wrong i'm sure...