Unfortunately, you're likely not going to find much information here. We purposefully do not track DLC unless it's released in a physical format, and even that is contentious at best.
I could point you at quite a bit of information for PS3 and Xbox 360, but unfortunately there aren't any enthusiast websites that I'm familiar with for Wii DLC. There's also the problem of delisted DLC...
You're probably familiar with this, but there's a Wiki started to track some of that information:
http://nintendo.wikia.com/wiki/DLCBesides Rock Band and Guitar Hero, there were very few DLCs released.