Korg DS-10

[silent sniper]

Korg remade their famous synthesizer MS-10 for the DS. Currently only out in Japan, but you can import it from Play-Asia or pirate (the whole game is in English).
http://aqi.co.jp/product/ds10/en/index.html#hd-ds10

really fun to mess around with, I haven't really figured out what anything does yet.