New Ending on the Maw: Beat The Maw on Legendary and you will get a new ending. If you are wondering if you will get to see the master chief's face... you don't. Sorry to dissapoint you. However, the ending features a human and covenant fighting, and then the elite hugs the human, and then the ship blows up.
Killin Flood Easier: Use the shotty (shotgun).
Skip 3/4 of Assault on the Control Room: First, you need to be in co-op. When you come to the first bridge on that level, jump as far as you can to the left and land on that ledge. Walk down the ledge till you come to a "V" angle in the ledge. Now, the other person should kill themselves. Right before they spawn, just walk barely over the ledge. You will hit the ledge below it and slide off. If you did this correctly, the other person will spawn on the ledge. Wait till you spawn and walk as far to the right as you can, until you are over a rock. Jump off the ledge and "ski" down the side, and you will land on the ground un-hurt. You will also have no more enimies to fight!
Flying Grunt: Where you cross the bridge, and all the little guys are sleeping, press B to hit them and quickly kill them. Leave one on the left or right still sleeping. Throw a plasma grenade on the turret. They will scream and sometimes get in the turret. Get back and watch the him fly out of the turret and fall to the ground very far below.
Grunt message: There is a Grunt in The Maw that will give you a message. To get to him, go all the way past where the drop-ship is going to pick you up. About three rooms after that, there will be a shortcut to your right. Go in it. In the middle will be two doors, to your left and right. Unlike the shortcuts, the door to your right will be open. Enter it. At the end of the hallway, get out of the jeep and the Grunt will be there. He tells you something that sounds like "It's a good thing there was food on this Starship cuz I worked up a big mighty thirst!"
Insta-Kill: Melee any enemy from the back.
Blood Gulch Sniper Perch:
Well, thats really hard to get to, to see the vid of how to get there,
Ah, Help me!: Go to any level that has Ghosts. Reduce the Ghost's life to one red bar. Go to a high location where you can land and stick a plasma grenade to the inside of it. Quickly get into the Ghost and fly forward. The grenade will explode and Master Chief will fly out in front of the flaming Chost looking as if he is running from it
Rocket Jump: Wanna jump really high? Well then get a rocket launcher, aim it at your feet, and jump. While you are going up, shoot the rocket launcher.
Flying Vehicles: Go into co-op and play a level with vehicles. When you wanna get the vehicle over something, or just wanna fly it, here is what you do: Have the first person stand right behind the vehicle. The second player then needs to melee the first. Make sure NOT to get their grenades. Then, the first player should respawn and melee the second player in a different part of the vehicle. Then, the first player should pick up ONE, and ONLY ONE grenade. Then, throw it under the vehicle. It will then go flying hundreds of feet in the air.
On top of the silent cartographer: Play on that level until the echo crashes. Go down by the crash site and pick up a rocket launcher. Get in the warthog and drive up to the security facility. Park the warthog in a place that it close to the to of the facility. Throw a plasma grenade under it, and it should go flying. Then, shoot it with your rocket launcher to make it go higher, so it goes on top of the facility. Then you should rocket jump up there. Once you are up there you can get massive air by driving off the cliffs.
More tricks will be up soon