Super Mario Galaxy Cheats

I'm looking for any fun info about super Mario Galaxy, whether it be cheats or stupid trivia or important things to know.

This is what I have so far:
Unlockable: 121st Star

There's actually 121 Stars in the game, not 120. To get it, you must first have all 120 Stars. This unlocks Luigi. Beat the entire game with Luigi, defeating Bowser at the end. After this, a new galaxy will be unlocked. Finish this final galaxy to get the 121st Star.

Unlockable: Luigi

Here's how to get Luigi. First, get all 120 Stars in the game. Then, return to Rosalina (on the Comet Observatory) and request to fight Bowser one last time. Defeat him and let the credits roll. Thereafter, a message will appear telling you Luigi is a playable character.Luigi controls slightly differently than Mario; in fact, the differences mirror those in Mario All-Stars' Lost Levels. In short, he jumps much higher (making some puzzles easier), but he has less traction, so he slides around a lot more.