Lifehacker had a neat article recently about softmodding your Wii, for homebrew apps & dvd playback.
http://lifehacker.com/400581/hack-your-wii-for-homebrew-apps-and-dvd-playback Considering it's a softmod, it's fairly harmless, and easy, as mods go. I did it without too much trouble, testing the dvd playback at the moment...