OMG, I thought of the best game(s) to port to the DS: Abe's Oddysee & Exodus on the PS1. You could use the microphone to say the phrases instead of remembering button combinations.
To be honest, I only suggested this with only the microphone in mind. I've never played the games on PS1. Well, I have, but not all they way through. I have no idea what the touch screen could be used for, or whether the games are small enough to fit onto DS cards.
If anyone has played/owned/completed these games, please discuss your thoughts on a port for DS.