A cool glitch is to be able to shoot through walls with the tank.
You aren't really shooting through the wall, your gun is through the wall. This glitch can be hard to do sometimes, and easy other times. Simply move the tank so that it is as close as possible to the wall you want to shoot through, for example a base in blood gultch. Nest move the end of the turret so that it is sticking through the wall, and in the room the enemy payer is in. Now simply shoot, hopefully it works and kills the enemy. This works best with thin walls.

One of the few glitches in halo is that you are able to get on top of the level in sidewinder.

First you have to drive a tank up on the first teleport area.  Get the tank set so that it is infront of the cave area that you can go through the teleporter, the tank should be facing the teleporter.  Next bring a ghost up there and go full speed at the tank then you will fly up on top of the level, hopefully with the ghost.