I'm a zombie/resident evil stan which is the main reason why I bought a Wii. I always wanted to play the Remake of the first Resident Evil.(But couldn't because Capcom never ported it to xbox or PS2/PS3) There's also Resident Evil Zero (A prequel to the first Resident Evil) for the Wii and two Resident Evil shooter games on rails that are worth checking out.(You get to relive alot of the events of RE 1 thru 3 with modern graphics) Most people also agree that the Wii version of Resident Evil 4 is the best version.
Resident Evil Remake ........if u never played the gamecube version.
Resident Evil Zero (Same as above)
Mario Galaxy is a must cop.....I have yet to get the sequel tho, will cop soon.
Super Smash Bros brawl. (If u were a gamer in the 90s it was everyones dream to see Mario and Sonic fight, this game makes it a reality)
Donkey Kong. (Some ppl say its even better than Mario Galaxy)
Xenoblade (its the best japanese RPG since FFX)
Mario Kart can be challenging and entertaining also
Sonic Colors is the best sonic game to drop since the genesis days....(that and Sonic Generations of course)
Plus there are two Zelda games on the system you should check out....both got near perfect reviews from critics
I mainly only turn on the Wii for Mario Galaxy, Zelda and Resident Evil remake tho