Press Start to pause game play, then enter one of the following codes. There is a five minute lockout before a code can be re-enabled. To bypass this, save the game after a code has been enabled, quit the game, then reload your saved game.
$5,000:
Pause game play, then press X, Y, X(2), Y, click Left Analog-stick.

Full ammunition:
Pause game play, then press Y, Left, Y, Right, X, click Right Analog-stick.

Full health:
Pause game play, then press Left, X, Right, Y, Right, click Left Analog-stick.

All movies:
Pause game play, then press Y, X, Y, X(2), click Left Analog-stick.

Achievements:
Complete the following achievements to unlock Xbox Live Gamerscore points.

First Sign of Respect (5 points): Reach Respect Level 10.
Gaining Respect (10 points): Reach Respect Level 20.
Making an Impression (15 points): Reach Respect Level 30.
Demanding Respect (20 points): Reach Respect Level 40.
Jack of All Trades (25 points): Reach Respect Level 45.
Public Enemy Number One (50 points): Reach Respect Level 50.
Assassin (10 points): Earn 5 Execution Styles.
Petty Theft (10 points): Crack 10 Safes.
Negotiator (5 points): Bribe a Police Chief.
Smuggler (10 points): Hijack 10 Racket Trucks.
Real Estate Investor (10 points): Purchase a Safehouse.
Bodyguard (10 points): Hire a Crew Member.
Earner (10 points): Extort 10 Businesses.
Enforcer (10 points): Take Over 5 Rackets.
Arms Dealer (10 points): Purchase a Firearm Upgrade.
Forced Entry (10 points): Heist a Bank.
Demolitions Expert (10 points): Bomb a Business.
Knockout King (15 points): Win a Prize Fight.
Entrepreneur (15 points): Collect 10 Film Reels.
Neighborhood Control (20 points): Take Over a Neighborhood.
For the Family (25 points): Complete all Missions.
Contract Killer (25 points): Complete all Hits.
Service Provider (25 points): Complete all Favors.
Diplomat (20 points): Help all Merchants.
Total Domination (50 points): Extort all Businesses.
Front Man (50 points): Take Over all Fronts.
No More Narcotics (30 points): Bomb all Drug Rackets.
Warehouse Wrecker (30 points): Seize all Warehouses.
Transport Takedown (30 points): Seize all Transport Hubs.
Rival Family Elimination (40 points): Destroy all Rival Compounds.
Real Estate Mogul (20 points): Purchase/Own all Safehouses.
Bank Robber (10 points): Heist all Banks Once.
Heavyweight Champ (25 points): Win all Prize Fights.
Safecracker (30 points): Crack all Safes.
The Don (25 points): Reach Don Rank.
Don of NYC (50 points): Reach Don of NYC Rank.
Executioner (40 points): Complete all Execution Styles.