Yes potentiometers would not have been as cool...
Anyway I used the DS touch screen because I had one lying around... I only did the project to find it a use,,,
As far as I know, the DS LCD screens themselves have not been connected to the arduino but it should be possible with another board including ram and another IC like they have on the arduino touch shields... You would probably have to make it yourself though and unfortunately I do not have that much expertise...
Btw, if you want to comment on any other projects I could do or take a look at the pile of stuff I have then please look at:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1243337100
Mowcius