[brodie]

Tune the keys to different scales on different days. Have it play certain themes on important days and holidays when you step through it in sequence.

Personally I'd like to hear some video game-style level up music whenever I climb to the top.

[modelic3]

Nice. I just dismissed the tuning aspect completely.

[klipt]

Ok, but then you should take care to make it look different. Having the keys laid out like a piano keyboard but playing the wrong notes would just be ... wrong.