Zelda Twilight Princess Glitches

Cave of Ordeals Glitch
Put out the torches with the Gale Boomerang, and the door on the next floor will open, although this excludes floors floors 1, 10, 11, 20, 21, 30, 31, 40, 41, and 50. This exploit only works on the Wii version of Twilight Princess.

Die in Ordon
Go into the pool of water ear Rusl's house. Equip the clawshot and use Z-target. Move towards the slope ext to Rusl's house, and this will cause Link to teleport to the entrance of Ordon with one heart fewer.

Get the Master Sword Early
You need access to Faron Woods in Twilight without the North Faron Woods Twilight Portal. Play to the point where Link steals the equipment from Ordon. Go to the North Faron Woods Twilight Portal, and fight the Shadow Beasts there. Near Trill's shop is a low section of the cliff that surrounds the area. Face this part of the cliff and get a Shadow Beast to move in front of Link. Use Midna's energy field attack to kill it.
If done right, you should now be on top of the cliff! Run accross the cliff until the Sacred Grove path appears on the map. Go through the wall in the direction of the grove, and continue the game normally until you get to the Master Sword!
If you don't quite understand what I just said, this youtube video should help you:

Get to the Field South of Castle Town
Exit the Castle Town from the South Gate. Call Epona, and ride over to the huge pit. Stop just beside the pit, leaving a bit of space between it and Epona. Transform into Wolf Link, and talk to Epona so that she pushes Link into the pit. By now you should be in the Lake Hylian river, and can now explore it!