Nintendo is working on some sort of storage solution of their own, but to those of you who can't wait, the WiiZii is on its way.
We have few details at the moment, but here's a shot of a WiiZii prototype installed. It can connect an external SATA drive and features a tiny bit on onboard storage so that the chip's firmware can be updated as needed. With the use of the WiiZii+drive, you can load mass amounts of homebrew files quickly. In fact, I daresay that with a large enough drive, you could load far more content than is actually worth playing on the Wii.