I haven't had too much time on my hands to come on here recently so I decided to put down my controller and make some. It seems Bungie made it easier to get out of Bounds on purpose or something. I don't know if anybody has mentioned these yet so I'm gonna post em all here anyway. (If I don't have an O.O.B.{out of bounds} for each level yet, I'll probably find some in the future and I'll repost this.)
Cario Station-(the one where you go out in space)-(2nd level i think)-as soon as you first step out of the air-lock leading to Cario's shell, look dead ahead and you'll see a slanted pillar thing behind a crate.(the pillar is more like a huge right triangle from the floor to the top of a wall.) Climb up it by jumping at the base. Once you're on the wall, make a right and go straight. and you're out(it's really that easy). Every now and then, you'll hit an invisible wall so you're gonna have to take detours.
????-(the 1st Earth level)-(Zanzibar Hotel)-When you first ge out of the ship, stop right in the 1st doorway. Look up and you'll see a light. Go find a plasma grenade and come back to the light. Jump on in and figure a way to get the grenade under you but not sticking to you. You'll have 3seconds to jumps so time yourself and do it right. Once youre up your up. (again, its really that easy)
Metropolis-(starts you on a bridge)-(huge spider)-This one has a lot of cool stuff in it:) but it's also a bit tricky. Get to the middle of the bridge where there is a hole in it. as soon as you hit a checkpoint, get out and kill ur passengers because they'll shoot down the banshees you need. kill of 1 banshee and the big ship to the bridges right. Once you hijack the remaining banshee dodge the big ships attack and shoot the three guns off. Right about now it'll start fleeing so chase it to the end of the highway. It'll start to lower a shade and heres youre chance to jump out and onto the plane. It'll carry you out of bounds and the invisible wall won't effect you, it only effects banshees. Also... there is another cool thing i found... Later in the level, when Cortana says there some marines in a building who need help(she wants you to go into the building where there is a gunner on the roof and the scarab is coming straight toward you and shoots the tank), don't go in, rather grab a warhog and go up the second ramp(the ramp closest to the entrance where like 3 marines are standing. park it and get on the roof. Shortly afterwards, you'll see a pelican zoomin in and it stop like right above you. Jump up and press "x" (eventhough it doesnt say to) and you'll board the craft. at the end of it's flight, it slams into the ground and does ton of freaky unpredictable flips that are hard to dodge. Chances are you'll die the first time. For some odd reason, the pelican sometimes crashes in the water but you levitate. Its cool, try it. Now, this trick is 2 in 1. (EASY MODE)Grab a hog at the beggining of the level. drive to the end of the bridge and you will see a tunnel. Drive down the ramp backwards so the banshees flying around outside notice you and come in after you. When you get to the first half closed door, kill your marines so they dont shoot down the banshee. Figure away to get the banshee to follow you through the big yellow doors then kill all the ground units in that section. Again, there is another set of closed doors you need to figure away to get the banshee through. once its through, blow off a wing so the banshee can fit through a tunnel you'll come across l8er. Get the banshee to follow you into the room w/ red lights, pause get a drink and resume. Now the banshee is trapped in this room so u don't have to worry about it flying away from here on. Get it to lead the way down the tunnel and stay close to it. As soon as you see loading... appear on the screen, click "x" to board. if you did it right, you've got a banshee good to go. As soon as you get out of the tunnel, fly straight towards the bridge above and grab the cool new object on it. Or, fly to the door exiting the room w/ 4 waterfalls and look at the building thats broken near the middle. Fly into the whole and here's another freaky new object.
Delta Halo-(Huge pyramid in the middle)-(confusing ruins)-This one is really easy... When u first crash land, beat all the bad guys that come after you. Go straight through the valley like youre playing normally. You'll see like 3 sniper jackals. The one on the left is by a rock. Remember this spot as "A". kill the guys and get picked up by a warthog. Travle a bit until you are able to hijack a ghost then do so. Go back to A and wing around the back of the rock if u can. Hold down the a button so the front of the ghost lifts and boost it and you should strart slowly climbing the hill. Once ur past that first hill, the ghost can climb almost anysteepness so have a blast (your can go under water w/o dieing)

P.S.- I also sent this to the webmaster along w/ a lot of pics so hopefully you will understand better when my pictorial guide comes in