This is a prototype board for the Nintendo Game Boy Color. This is the type of board that would be sent to game developers to test their game code before Nintendo had the production units ready. If you look closely you will see it has all the parts of a Game Boy: Starting at the upper-left and going clock-wise you will see the two LED-looking IR transmitter/receiver. Then the large cartridge port, little white plug (forgot), GB Link connector. Down the side is the volume control (the big round thing is the speaker) and then the headphone jack. The big grey thing is the power port (it uses a SNES power supply). On the other side- the red circles are the controls, and of course the LCD display directly above them.

Back of the board (which is fairly un-eventful):

And here's a picture of the unit running a game (taken by the person that sold me the board):