SSBB, Metroid Prime Trilogy, Zelda:TP, SMB:Wii, No More Heroes 2 (releases on 1/26, but I've played an advance copy and love it. It's a must-buy title), MadWorld.
Unfortunately, third party software has an abyssmal sales history on Wii. Ea, which originally announced more support for Wii in '09 and beyond, has decided to limit platform support (EA Sports like Tiger Woods and tennis titles will remain), and Capcom has announced that it will focus its attention on PS3 and 360, but not Wii. Others are following suit. Nintendo placed too much faith in gamers' desire to play previous-gen styled titles in a next-gen environment. In terms of gameplay and graphics, Wii is not much better than GameCube, and the Wii-mote has become more of a handicap and novelty than widely-adopted controller. I have a hard-on for Nintendo, and always have, but I'm disappointed with the long-term outlook. Nintendo prints money, and always has, but it has to step up its game if it wants to continue to appeal to the core gaming community.
Also, check out what's available on Wii Virtual Console. There are a lot of great retro titles to download, but you'll need to by the classic controller for most of those games.