Really depends on what you like. Here's my list, in no particular order:
A Boy and His Blob
Little Kings Story
Metroid Prime Trilogy
Okami
Dead Space Extraction (can be played co-op)
Zack and Wiki
Muramasa
The Conduit
Dawn of Discovery
Lego Indiana Jones (can be played co-op)
Cursed Mountain (if you get the hang of the controls)
Resident Evil 4 Wii (even if you played it on another console)
Deadly Creatures
Tenchu: Shadow Assassins (opinions differ on this one)
De Blob
Mario Kart Wii
Excite Truck
Excitebots
Zelda Twilight Princess
NPC Pikmin
Shaun White Snowboarding (play it with the Wii Fit balance board)
Tiger Woods PGA tour 10 with Motion Plus
Punch Out
Klonoa
Minigames or not, you really owe it to yourself to buy Wii Sports Resort.
Wiiware:
World Of Goo
Swords & Soldiers
Lostwinds
Lots of VC titles (Zeldas, etc).
Coming up:
New Super Mario Brothers Wii
Resident Evil: Darkside Chronicles
Final Fantasy: The Crystal Bearers
Tatsunoko vs. Capcom
Silent Hill: Shattered Memories
Fragile
Arc Rise Fantasia
Red Steel 2
Monster Hunter Tri
Currently Playing: Shin Megami Tensei: Devil Survivor Overclocked, Professor Layton and the Curious Village
Anticipating: Xenoblade, The Last Story, Mario Kart 7, Rayman Origins, Zelda SS, Crush3D, Tales of the Abyss 3DS, MGS:Snake Eater 3DS, RE:Revelations, Time Travellers, Professor Layton vs. Ace Attorney, Luigi's Mansion 2, MH TriG, DQ Monsters, Heroes of Ruin
