Dell.com is having a 20% discount on the Wii and DS so I ended upgrading my gaming experience to the next level (for a cool $209.99 after shipping). The first purchase is going to be Mario Kart Wii, of course, but I am out of the loop on what's worth buying for the Wii.

Is Zack and Wiki and No More Heroes any good? any other recommendations?

They are both great. I beat Z&W already, and am working my way through NMH. Other than the slew of Nintendo games, Mario, Zelda, etc. you might wanna check out MadWorld, depending on its reviews. Other than that, de Blob, CoD:WaW, Shaun White, House of the Dead: Overkill, and Boom Blox come to mind

World of Goo (Wiiware)

Zack & Wiki

Galaxy

Wii Fit

Those are the four best experiences other than Wii Sports on the system. If you can get Nights or the first Sonic Wii game for less than $30 they are well worth it - they have amazing levels hidden behind much more mundane levels but the amazing levels are worth every penny.

Get Brawl! I just bought Zack and Wiki, it's pretty good so far.

Depends on tastes...My top 5 games for the wii are SMG NMH De Blob Brawl and Zelda....Also buy a few thousand wii point's for many classic games...

Twilight Princess
Super Smash Bros. Brawl
Super Mario Galaxy
Metroid Prime 3: Corruption
No More Heroes
Call Of Duty: World At War
Battalion Wars 2
Mario Strikes Charged
Super Paper Mario

Mad World is way up there on the list too. Does Shawn White utilize the Wii balance board? If so then it's a no brainer.

Yes it does.

No More Heroes is by far the best game on the Wii.

Brawl is absolutely a must have