Super Meat Boy Cheats

Play as Brownie
Enter the code on the character selection screen before starting a level, then select a character (most characters will work, but not certain ones like Gish and Alien Hominid). Brownie is just like Meat Boy, but shows up as a question mark on the leaderboards. You must beat the boss at the end of the Salt Factory first.

Play as Brownie: RB, RB, RB, B, B, B, X

Achievements
Business Time (10): Collect 50 bandages.
I'm A Golden God! (20): 100% the game
Iron Boy! (10): Complete a full chapter without dying.
Living in the Past (20): Find and complete 5 warp zones.
Nostalgia (15): Find and unlock a warp zone.
Sticky fingers (5): Collect 10 bandages.
The Commander (10): Find and unlock Commander Video.
The End (65): Complete the main game.
The Real End (20): Complete the Dark World.
Tin Boy (5): Complete 10 levels consecutively without dying.

Avatar Awards
Super Meat Boy (Male/Female): Beat the Light World.
Super Meat Boy T-Shirt (Male/Female): Play the game for a few minutes.

Unlock Brownie Gamerpic
Brownie Gamerpic: Beat Brownie in a Race

Teh Internets
Teh Internets is an unlockable online only chapter that contains bonus levels.

Teh Internets Chapter: Collect 20 bandages

Unlockable Characters
Characters you can unlock through Bandages or Warp Zones.

4 Color Meat Boy: Collect 80 bandages
4Bit Meat Boy: Collect 60 bandages
8Bit Meat Boy: Collect 40 bandages
Alien Hominid: Collect 30 bandages
Commander Video(Bit Trip): Warp Zone in World 1
Flywrench: Complete The Fly Guy! Warp zone in 4-18
Gish: Collect 10 bandages
Jill (Mighty Jill Off): Warp Zone in World 2
Meat Ninja: Achieve 100% completion
Ninja (N+): Collect 100 bandages
Ogmo (Jumper): Complete The Jump Man! Warp zone in 3-16
Pink Knight (Castle Crashers): Collect 90 bandages
Spelunky: Collect 70 bandages
The Kid (I Wanna Be the Guy): Complete The Guy! Warp zone in 5-7
Tim (Braid): Collect 50 bandages