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.

Some other RPG classics that probably could be ported:
- Ultima 7 - http://exult.sourceforge.net/
- Ultima 8 - http://pentagram.sourceforge.net/