I love the Wii as a console, but the fact that the nunchuk is wired to the remote always annoyed me no end.
I find myself avoiding games or sports that require the nunchuk to be used - especially something like boxing, where you're supposed to be flailing around - I don't want to be tethered in these moments of wild action.
I know, right? You thought I was so quiet and mild-mannered.
I picked up the
Nyko Wireless Nunchuk this morning - typically I'll research a product for at least a few minutes online before buying a 3rd Party Accessory, but I decided to wing it for once.

It works well, (though I managed to cut my thumb opening the blister pack - not with a knife or scissors, but with the plastic itself) it synced up right away and seems to function just like a wired nunchuk.
I tried out Wii Sports (Boxing), Mario Cart (I won 2 out of 3 races) and last of all, Harry Potter and the Half-Blood Prince (Rental from GameFly).
The wireless nunchuk works well as long as you're playing games that do not require the 'Wii Motion Plus' attachment to the Wii Remote.
I don't know how many games use Wii Motion Plus, but lately spending all my Wii time playing
Wii Sports Resort, which requires the WMP.
There's a handy pass-through port on the bottom of the WMP. Unfortunately, the wireless nunchuk transmitter does not have a pass-through - if it did, I wouldn't be returning it.
It's not possible to plug in the wireless nunchuk transmitter for 2 reasons:
1) The shape of the nunchuk transmitter is designed and contoured for the bottom of the Wii Remote, which has a rounded bottom.
The bottom of the WMP is far different - it flares out instead of curving in, and even has little feet which would allow you to stand the remote on its end (for some reason).
You could choose to grind or cut the WMP feet or remove the up-curving edges of the nunchuk transmitter, but this would likely lead to cracks in the plastic.

2) The rubber jacket of the Wii remote would interfere with a solid connection - you could discard the rubber jacket or trim it, I suppose.
I'm sure Nyko or another accessories company will develop a transmitter to work with the WMP, but this one does not.