The Legend of Zelda: Twilight Princess
Wii Cameos

Fyer's Bullet Bill

Head to the bottom of Lake Hylia where you will find a clown named Fyer running the cannon shop. Look at his left arm and you will see artwork of Bullet Bill from the Super Mario series.

Falbi

Submitted by TrustTheFungus

Legendary Hyrulian Master Fisherman

Visit the Fishing Hole in Upper Zora's River. One of the pictures on the wall shows the Fishing Hole owner from Ocarina of Time as he appeared on the N64. The new owner calls him the Legendary Hyrulian Master Fisherman.

Ocarina of Time Fishing Guy

There is evidence that the current Fishing Hole owner is a descendent of the N64 Fishing Hole owner, as they both appear to suffer from the same itchy back.

Submitted by Leon, TV Eye

It's a Secret to Everyone!

Head through the empty shop filled with Gorons in Hyrule Castle Town until you reach a balcony. The Goron out here sells you arrows. The first time you speak to him he will say "It's a secret to everyone!"

This line is taken from characters in hidden caves in The Legend of Zelda (NES).

Submitted by Smashchu

Malo & Talo

Two of the children in Ordon Village are named Malo and Talo, inspired by the characters Malon and Talon from The Legend of Zelda: Ocarina of Time.

Submitted by Doom 5500

Howling Stone Songs

Throughout Hyrule you will find Howling Stones, rocks marked with the Sheikah icon with a hole through the middle. As Wolf Link, you have to howl along to the musical wind that blows through them.

Nearly all of the songs are from earlier The Legend of Zelda series games.

Submitted by Boo Destroyer, additional information from Zelda Wiki