The NES has an emulator on Maemo and it there were some classic AD&D games on it. Possibly some other emulators too. Maybe you were referring to the newer classics of the the late 90s though.
Dosbox is coming as well, wouldn't mind playing the Eye of the Beholder games.
Though when I first read the topic here I was hoping it was on playing actual D&D! I wouldn't mind having a character sheet manager on my phone for game nights.
There was also the old Amiga classic "Dungeon Master" but porting seems to have ceased and I don't think it runs as is on the N900 ?. Here is a link to another discussion where you'll be able to find it. http://talk.maemo.org/showthread.php?t=36493