The ideas of using LCD's and scrolling LED marquees have both ben considered. One guy even got an LED scrolling sign to owrk with his cabinet through a hacked version od Arcade OS (for got the site). I think he had to program each game, though. And as we know there are thousands.
An LCD screen would be infinitely easier to program, though, and it would be prettier. About the only thing making it less than ideal is the shape and size. However, you could trim the image on the screen to fit the proper marque shape or you could use a full-screen screen shot of the game title screen.
A good front-end programmer could probably code that last part in a day. Almost definitely if given a week. (However, I'm not a good front-end programmer.)
At that point the only prohibitive barrier is the cost of an LCD screen.
By the way, when I say LCD screen I'm not refering to those dinky lil things people throw on there computer cases to show time and temperature. I'm talking about LCD monitors with a VGA interface. Those lil LCD screens would be difficult to program, too, unless they had s-video or RCA in (like car flip-down screens).