Ultima Underworld 1 and 2 were both severely awesome RPGs. I believe you could play those with a cab. I dunno, it might require a trackball or mouse, but if I remember they had keyboard keys for lots of things.
Gothic is fun to play on my cab. I don't know if it's dos or not... I'm running it in windows.
I remember a "Jill of the Jungle" from the dos days too. A NES or SNES emulator would be cool. I remember there being lots and lots of fun side scrollers for dos, but I have no idea where you'd find that software nowadays.
BTW if you want to try Ultima Underworld, you should, *ahem* um, talk to me privately (*gestures to inside of trenchcoat*). I would love to see if it works properly under DOS. I haven't been able to get the player to move correctly in either game since PCs topped the 300 MHz mark. I'm wondering if the speed of the CPU causes a problem with the game, and I don't have any systems that can have dos installed on them. My theory is that the game is internally running at such a high frame rate that it causes a problem with the player's velocity or position variables and the floating point precision of the code. He only seems to move in cardinal directions now, when I know the movement was fine back when I ran it on a 486.