I'm starting to feel the pinch for a third and fourth wiimote, but I'm not sure the nunchucks are necessary. I can't think of a 4-player game that requires nunchuck, can anybody else?

I'm pretty sure you would need that set-up for Rayman Ravid Rabbids 2, but I do see your point.  I think that that would be the exception and not the rule.

Strap your Wiimotes to a pair of dumbbells. WiiFit 2!

don't forget gamecube/classic controllers!

 Wavebird is better for the GC titles... but the classic controller is better for some of the VC titles. So one of both at least.

I'm pretty sure the Wii gun was supposed to come with pack in, but also be involved in bundles with Ghost Squad and Umbrella Chronicles, which probably would be what... 10 dollars more then the versions without them?

Or was that just rumors?

 You can play 4 player Elebits with 1 nunchuck, but then the nunchuck user gets to control the camera for the entire game.  I prefer to play with all 4 nunchucks, and set the camera on random, so every 30 seconds somebody new gets control of the camera to mix it up.  It's more fair, more fun, and much crazier.  And 11 months ago  I played some 4 player Red Steel with all 4 nunchucks.  I haven't used 4 nunchucks in forever though.  I just moved and went back to school and barely have time for 1 player games as it is.

Most of that stuff goes in a small box, and the bigger ones easily fit under a bed/coach, or against a wall. The amount of stuff is probably going to get pretty insane in a few years though. =/

what's gonna happen for multiplayer mariokart?
one person with a steering wheel, 3 without?

Attach a regular small bow to the zapper and you get a crossbow.
You can probably find some of those in the toys section.