Update: Apparently nobody can get this to work, so it may be a steaming pile of crap or turn out to be specifically based on some hard drives. The Google docs page has gone missing and we're looking for updates.
While Nintendo may catch much grief for making their backwards Friend Code system completely manual and laborious, we have to hand it to them -- they nailed pc-class hard drive support. While performance over USB may not be killer, you can get the job done without breaking the bank, raising much tech fuss, or even using a screwdriver. It's easy as 1-2-3:
1- Download the latest firmware on your Wii
2- Format the USB hard Drive to FAT32, maximum 120GB
(Though some website claims that a 300GB hard drive works too)
3- Remove Any SD card form the SD slot
The Wii should detect your USB hard drive as an SD card. Beautiful!
So how does it stack up on value? Nicely. You can either pay Microsoft $100 for a 20GB (this will reportedly go down soon ... but judging by the 20GB ripoff we doubt it will be that much better) or you can add a hard drive five times bigger on to your Wii for half the price.
Granted, the point may be moot as you really can't do much on your Wii with a hard drive yet other than certain piraty things, but it's nice to know. The PS3 gets second place for the belly rip out and replace hack. Until then, here's a naughty tutorial on emu gaming on the Wii. Tisk tisk!