Connecting 4 DVI (or VGA) monitors to the Macbook Pro Retina
You could run 2 DVI/VGA montiors via the thunderbolt ports with adapters, and 1 via HDMI. I believe the 4th would need to be connected with a USB-to-vdeo adapter.

Check out this question for some more information:
How many external displays can I power with the 15&quot; retina MacBook Pro?