The Great Banshee Switch

The Great Banshee Switch is a trick performed in Halo gameplay using two airborne, piloted Banshees. It involves players switching their respective vehicles in mid-air.

Process
This stunt requires great skill, faultless timing, and sometimes just pure luck. First, both players must be flying in the same direction, and at the same speed. The first player must position and situate his Banshee directly above the second player's Banshee, and just a few feet forward. At this point, the Banshees should be touching. Now, both players must get out at the same time, and when they are close enough, they must hold X (the Right Bumper in Halo 3) to get in the other player's Banshee. If done correctly, you will switch Banshees in mid-air.

This technique can be used if your Banshee is about to be hijacked. Just barrel-roll upwards as you are about to be kicked out and you will be flung upwards. You may then fall down on the Banshee and hold X/RB to re-board. A way to counteract this is, when you get in the banshee immediately boost away, then they will not fall back to the banshee to re-board it.

This trick is also useful for players in campaign. When you are in a fight with other Banshees, simply fly over an enemy's Banshee, hold X/RB, try to fall onto the enemy's Banshee, and then board it. This, however, is the most difficult method, as the enemy will often turn and flip a lot as to get in position to shoot you.

Other Banshee Tricks
With practice and a lot of patience you can master these other Banshee Tricks. Some exploit the glitches in Halo, while others are just pure skill: This trick requires a bare minimum of 2 players and 1 Banshee. Have Player 1 enter the Banshee, who will fly low over Player 2. Player 2 will hijack the Banshee. A third of the way through the boarding animation Player 1 will perform a backflip. This will cause him to fly up above the Banshee. When Player 1 Comes back down have him board the Banshee. A third of the way through the boarding animation Player 2 will perform a backflip. Continue this cycle for as long as you're capable.
 * Banshee Juggling:
 * While playing Capture The Flag or a similar game have the team member with the "flag" jump onto the Banshee and then race to the objective. This can lead to some very quick flag or bomb scores.
 * If you ever get jacked while in the Banshee and you are near a wall, you can actually splatter the hijacker off by rolling sideways into the wall. The cool thing about this is that after you splatter the guy, the Banshee's hatch stays open.
 * Another anti-hijacking trick, if you are boarded, exit the Banshee just before your opponent would usually throw you out, and then hold X/RB really soon after. This makes it so that when your opponent hops into the vehicle in the appropriate part of the boarding animation, you will board your recently stolen vehicle before they have a chance to move, taking it back and allowing you to fly away. This will also catch them off guard so that they won't repeat the trick on you. Practice this to get the timing down, even though it doesn't need to be too exact. In Halo 3, this counts towards an achievement.
 * When flying the Banshee in Halo 3, hold A + Forward on the Control Stick. If done right, the Banshee will drop quickly straight down, belly first. If you land the Banshee belly-first, then it will explode, and you will still have full shields. Useful if there is a lot of pressure on you, if you are being Missile-Podded, or just for fun. Landing on top of another vehicle or the Elephant will kill nearby enemies, and since it miraculously does no shield damage to you, you can clean up survivors no problem. Also, sometimes when this happens, you can be flung out, occasionally a long way.
 * If you are boarded and you want to kill the person who skyjacked you, simply throw a Plasma Grenade the second you are forced out of the Banshee. It will destroy the driver and the banshee; this works best in multiplayer.