A lot of this may have to wait for the next generation of systems, and some is impractical.
You could do some things now, like dual-wielding guns or attaching the Wiimote to different body parts, but many of these applications don't make for viable games for much the same reason that most PS2 games don't make use of the Eyetoy - your game effectively requires multiple controllers, so you lose a lot of potential sales. More gamers are going to have multiple controllers than have some other kind of peripheral, but it's not going to be all of them. Certainly once you go up to requiring three or even four remotes, your market is down to almost nothing.
Regarding more sensitive applications, like precise webslinging, 1:1 sword/hand use, or Leisure Suit Larry, the Wii might not be able to handle it. For the sort of analog (in the good sense - continuous) control that we're looking for, it seems to me that you'd need a fairly robust physics engine. Maybe it can do it, but I'm not sure. Not using set animations for different movements might also make things difficult - I'm sure that takes some rather hefty processing power.
Not that there's nowhere left for the Wii to go, but there are upper limits well below any imaginable use for a motion-sensing controller.







