I added a hand-made VGA "shield" to the Nano and used 3 digital I/O pins to get 3 bit color. I don't have a picture of the add-on board handy, but you can see a breakout game I made here: http://jrward.org/breakout.html
That project is actually kind of what convinced me to go ahead and buy the CV. It was fun, but it just felt like a lot of work making things that I could just already have on the board.