Hehe, yeah most things I do with Arduino is pretty hacky.
justfred replied to me separately that he figured out the problem by using "nunchuck_init_with_power()" instead of "nunchuck_init()". The former is used when you have have the nunchuck plugged directly into the Arduino (pins 2&3 supply power) while the latter is used when you have the nunchuck plugged into breadboard and powered from a proper supply. I really should've documented that better as it's confused a few people.
Thing is, with the blinkm in, it worked fine with just nunchuck_init() becase the blinkm was set to get power from those pins; but still caused some problem on the other side of the board.
Tonight I will have a nunchuck-driven piano!