It's much more fun when it's hacked. Then you can play old NES games and backup games.
Yeah, pretty much. If it wasn't for the Homebrew Channel I doubt I would have played the Wii much at all this year.
Anyway, here's some suggestions for games that fell under the radar. Best part about these games is you'll probably be able to get most of them for under $20.
House of the Dead 2 & 3 - Fantastic port of two light gun classics from SEGA.
Ghost Squad - An original (and deeper) light gun game.
Zack & Wiki - Monkey Island type Point 'n Click adventure game.
Dewy's Adventure - 3D Platformer
Kororinpa - Similar to Marble Madness (NES) or the Super Monkey Ball series.
Elebits - Exploration/Puzzle game
Klonoa - An enhanced port of the fantastic 2D platformer on the PSX. Pretty easy game.
Okami - Enhanced (kinda) port of this excellent PS2 Zelda clone.
Heavenly Guardian - Excellent co-op multiplayer game that plays like Pocky & Rocky (SNES). Or if you're not familiar with that game a top down Contra. I warn you though it's not an easy game despite its colourful graphics.
Castle of Shikigami III - 2D vertical shooter. Although again this game isn't easy.
Rune Factory Frontier - It's Harvest Moon with an RPG slant.
Blast Works - I know nothing about it, but it's supposed to be a pretty good semi-casual game.
Also the Phoenix Wright series will be getting released on Wii Ware each month starting in January (so the fourth game will be released in April) for about $8 - $10 per game. Quite possibly the best franchise to come out in the past decade.