Since most of the players on my cabinet are my daughter's friends (8-10 year old girls), I've put Happyland Adventures in the cabinet (
http://www.freelunchdesign.com/happyland.shtml), which is a freeware non-violent platformer. It's actually pretty addictive!
I used the older, non-Xmas version which I don't think is available any more. The Xmas one can load custom maps, but requires a mouse to do so (the ONLY part of the game to require a mouse) which is a stopper for me.
The only time I run into a problem with Happyland Adventures is when I get a high score, as the high score expects true keyboard input, so all of my high scores have blank names.
The other non-MAME games in my cabinet are the old Epicenter versions of Dragon's Lair and Space Ace. (My cabinet is DOS-based; if I was running Windows, I'd be running DAPHNE for these games...)