I really need help coming up with a way that I can control an 11 or 12 by 40 LED grid of 3 mm red LEDs. I was wondering if there is a way to do that with the arduino. Any help would be appreciated. I would like to be able to have animations play on the array. I am also looking for a way to drive 504 Bipolar red/green LEDs in a 36x14 grid, but that can wait. Thanks in advance.
Wow. Thats a big array. 
Did you need PWM on it or just on/off?
Hi, Ora
you might want to check this for the one-color-only matrix
http://www.arduino.cc/playground/Main/LEDMatrix
Eberhard