I just searched for wii nuNchuck arduino on Google and got about 90 000 hits, including this one : http://www.windmeadow.com/node/42 which may do what you want. Notice the second n in nunchuck not m (this may be why you weren't finding anything decent on Google et al).

Cheers

Amos

Edit:[Damn tuupola beat me to it by seconds]

Todbot wrote a tutorial for this a while ago. He also made a small nunchuck-breadboard adapter so you wouldn't have to cut off the connector of your nunchuck to get to the wires. Sparkfun.com sells these. If you really want to demolish your nunchuck, make sure you get a cheap one.