I have yet to acquire a Wii itself, but the Wii has a nice component called the Wii Sensor Bar.
Basically, this thing calibrates the Wiimote (the Wii controller), which allows the whole pointing thing.
I've "hijacked" the Wiimote's signals and hooked it up to my PC with bluetooth controllers and an application called GlovePIE. This is just a programmable input engine for stuff like joysticks, mouses, keyboards, etc, but it works very nicely with the Wiimote (and is also sorta especially programmed for it). Still, you need a Sensor bar if you don't want it all to be super choppy. The Sensor bar being connected to the Wii, me not yet having a Wii but having just a Wiimote, I wanted to use the Sensor Bar scripts !

What do you do? You make your own sensor bar.
The original:

Mine:
[Click for pics]

Hell, not only is mine wireless and has an on/off switch, but it also hogs a lot less power! The original one is 13V, mine is 6V.
What's the deal? All it does is power 6 (or in the original Sensor Bar's case 10) Infrared Light Emitting Diodes (IR LEDs), and the Wiimote does the rest. I simply put it under my monitor, turn it on, and I'm all set.

Hurray!