One other thing I'll say about ArcadeSD. And if any other JAMMA cards do this, please chime in. It allows for certain horizontal games to be played with a vertical monitor orientation.
This is not done through scaling, which would suck. Instead, with games that could be made to fit without affecting play, excess space has been removed (slight cropping); score and lives-remaining displays have been moved; and/or other random screen elements have been moved. The result is you get to play games like Missile Command, Zoo Keeper, and others on your vertical monitor.
Williams classics? Wizard of Wor? Nah, horizontal monitor only. But Clay did what he could to fit whatever he could make work.
Check out the current list of vertical games and see for yourself. Again, nothing was achieved through shrinking a game down and letterboxing.
http://destross.com/romsets/list/list.html