Call of Duty: Modern Warfare 2 Cheats

Blackjack (Bronze): Earn 21 stars in Special Ops.
Honor Rol (Bronze): Earn at least 1 star in each Special Op mission.
Downed but Not Out (Bronze): Kill 4 enemies in a row while downed in Special Ops.
I'm the Juggernaut... (Bronze): Kill a Juggernaut in Special Ops.
Ten plus foot-mobiles (Bronze): Kill at least 10 enemies with one Predator missile in Single Player or Special Ops.
Unnecessary Roughness (Bronze): Use a riot shield to beat down an enemy in Single Player or Special Ops.
Knock-knock (Bronze): Kill 4 enemies with 4 shots during a slow-mo breach in Single Player or Special Ops.
Some Like it Hot (Bronze): Kill 6 enemies in a row using a thermal weapon in Single Player or Special Ops.
Two Birds with One Stone (Bronze): Kill 2 enemies with a single bullet in Single Player or Special Ops.
The Road Less Traveled (Bronze): Collect 22 enemy intel items.
Leave No Stone Unturned (Bronze): Collect 45 enemy intel items.
Drive By (Bronze): Kill 20 enemies in a row while driving a vehicle in Single Player or Special Ops.
The Harder They Fall (Bronze): Kill 2 rappelling enemies in a row before they land on their feet in Single Player or Special Ops.
Desperado (Bronze): Kill 5 enemies in a row using 5 different weapons or attachments in Single Player or Special Ops.
Look Ma Two Hands (Bronze): Kill 10 enemies in a row using akimbo weapons in Single Player or Special Ops.
No Rest For the Wary (Bronze): Knife an enemy without him ever knowing you were there in Single Player or Special Ops.
Three-some (Bronze): Kill at least 3 enemies with a single shot from a grenade launcher in Single Player or Special Ops.
For the Record (Silver): Complete the Single Player campaign on any difficulty.
First Day of School (Silver): Complete 'S.S.D.D' and 'Team Player' on Veteran Difficulty.
Black Diamond (Silver): Complete 'Cliffhanger' on Veteran Difficulty.
Turistas (Silver): Complete 'Takedown' and 'The Hornet's Nest' on Veteran Difficulty.
Red Dawn (Silver): Complete 'Wolverines!' and 'Exodus' on Veteran Difficulty.
Prisoner #627 (Silver): Complete 'The Only Easy Day.. Was Yesterday' and 'The Gulag' on Veteran Difficulty.
Ends Justify the Means (Silver): Complete 'Contingency' on Veteran Difficulty
Homecoming (Silver): Complete 'Of Their Own Accord', 'Second Sun', and 'Whiskey Hotel' on Veteran Difficulty.
Queen takes Rook (Silver): Complete 'Loose Ends' and 'The Enemy of My Enemy' on Veteran Difficulty.
Off the Grid (Silver): Complete 'Just Like Old Times' and 'Endgame' on Veteran Difficulty.
Operative (Silver): Earn all 3 stars in at least 10 different Special Op missions.
Specialist (Silver): Earn 30 stars in Special Ops.
Professional (Silver): Earn all 3 stars in at least 15 different Special Op missions.
The Price of War (Gold): Complete the single player campaign on Hardened or Veteran Difficulty.
Star 69 (Gold): Earn 69 stars in Special Ops.
Platinum Trophy (Platinum): Earn all other trophies.

Unlock Modern Warfare 2 Museum
Museum is selectabe from mission select after Campaign is completed

Modern Warfare 2 Gallery Exhibition: Complete Campaign

Killstreak Rewards
Unlock certain kill-streak rewards by obtaining a certain amount of kills before dying.

AC130 (be the gunner of AC130): 11 Kills
Attack Helicopter: 07 Kills
Care Package (drops ammo/Killstreaks): 04 Kills
Counter UAV (scrambles enemy Radar): 04 Kills
Deplyable Sentry Turret: 05 Kills
Emergency Airdrop (Drops ammo/Kilstreaks): 08 Kills
EMP (Disables Electronics): 15 Kills
Harrier Airstike (choose drop location and defending Harrier): 07 Kills
Helicopter Gunner (be the gunner of a chopper): 11 Kills
Nuke Drop (kills everyone on map/ Wins Game): 25 Kills
Pave Low (Armed Helicopter): 09 Kills
Precision Airstike: 06 Kills
Predator Guided missile: 05 Kills
UAV (Show Enemy Location): 03 Kills

Multiplayer Weapons
Unlockable multiplayer weapons are based on your rank you receive. As you gain in rank, you will gain the ability for more and more weapons.

Assault Rifle (ACR): Rank 48
Assault Rifle (AK-47): Rank 70
Assault Rifle (F2000): Rank 60
Assault Rifle (FAL): Rank 28
Assault Rifle (M16A4): Rank 40
Assault Rifle (M4A1 Carbine): Rank 04
Assault Rifle (SCAR-H): Rank 08
Assault Rifle (TAR-21): Rank 20
Launcher (Javelin): Rank 50
Launcher (RPG-7): Rank 65
Launcher (Stinger): Rank 30
Launcher (Thumper): Rank 14
LMG (AUG-HBAR): Rank 32
LMG (M240): Rank 52
LMG (MG4): Rank 16
LMG (RPD): Rank 04
Machine Pistol (G18): Rank 22
Machine Pistol (M93 Raffica): Rank 38
Machine Pistol (TMP): Rank 58
Pistol (44. Magnum): Rank 26
Pistol (Desert Eagle): Rank 62
Pistol (M9): Rank 46
Shotgun (AA-12): Rank 18
Shotgun (M1014): Rank 54
Shotgun (Model 1887): Rank 67
Shotgun (Ranger): Rank 42
Shotgun (Striker): Rank 34
SMG (Mini-Uzi): Rank 44
SMG (MP5K): Rank 04
SMG (P90): Rank 24
SMG (VECTOR): Rank 12
Sniper Rifle (Barret .50 cal): Rank 04
Sniper Rifle (M21 EBR): Rank 56
Sniper Rifle (WA2000): Rank 36

Pro Classes and how to unlock them.
Bling Pro (Two secondary weapon attachments): Get 200 kills using a weapon with 2 attachments
Coldblooded Pro (No red crosshair or name when targeted): Destroy 40 Enemy Killstreak rewards while using cold blooded
Commando Pro (No fall damage): Get 20 Melee Kills using Commando
Danger Close Pro (Extra air support damage): Get 100 Kills with explosives while using danger close
Hardline Pro (Death Streaks require one less death): Get 40 killstreaks while using Hardline
Last Stand Pro (Use equipment in Last Stand): Get 20 kills while in Last Stand
Lightweight Pro (Quick aim after sprinting): Sprint 30 miles using Lightweight
Marathom Pro (Climb obsticals faster): Run 26 miles using Marathon
Ninja Pro (Foot movement is silent): Get 50 close range kills using Ninja
One Man Army (Swap Classes Faster): Get 120 kills using One Man Army
Scavanger Pro (Extra Mags): Resupply 100 times while using Scavanger
Scrambler Pro (Delay enemy claymore explosions): Get 50 close range kills using Scrambler
SitRep Pro (Louder enemy foot movement): Destroy 120 enemy devices using SitRep
Sleight of Hand Pro (Faster Aiming): 120 kills using Sleight of Hand
Steady Aim Pro (Longer breath duration for sniper scopes): Get 80 hip fire kills using Steady Aim
Stopping Power Pro (Increased vehicle damage): Get 250 kills using Stopping Power

Unlock Extra Custom Class Slots
Custom Class slot 06: Enter 01st Prestige
Custom Class slot 07: Enter 02nd Prestige
Custom Class slot 08: Enter 04th Prestige
Custom Class slot 09: Enter 07th Prestige
Custom Class slot 10: Enter 10th Prestige