Increase Fatigue:
During play, press B to bring up the options menu. Use L and R to switch to the Stats screen. Now select the 'Fatigue' meter and press Black, Black, White, White, Black, then press and hold A until the desired Fatigue level is reached.

Increase Health:
During play, press B to bring up the options menu. Use L and R to switch to the Stats screen. Now select the 'Health' meter and press press Black, White, Black, Black, Black, then press and hold A until the desired Health level is reached.

Increase Magicka:
During play, press B to bring up the options menu. Use L and R to switch to the Stats screen. Now select the 'Magicka' meter and press Black, White, White, Black, White, then press and hold A until the desired Magicka level is reached.

Unlimited Arrows:
When you are shooting arrows, pull back, don't let go, then press B and go into your menu. Unequip your arrows. When you return to the game, you'll still have an arrow notched.

Item duplication:
First, you need to enchant an amulet with a constant effect to summon Bound Boots/Cuirass/Gauntlets/etc. The bound item type should be the same type as the equipment you want to dupe. So if you want two pairs of Boots of Blinding Speed, you'd enchant the amulet with Constant Effect: Bound Boots. This will require a Golden Saint or Ascended Sleeper and small bit of gold. Equip the item you want to dupe, then put on the amulet. The bound equipment will replace the soon-to-be-duped equipment. Then manually equip the armor you want to dupe over the Bound equipment.

Now go let a monster hit you or cast Disintegrate Armor spells on yourself to bring the condition of whatever piece of equipment you want to dupe down to zero. The bound equipment will automatically replace the broken equipment. Then, remove the amulet, go out of the inventory screen, and then go back into the inventory screen and put it back on. Remove it one last time and you will have two pieces of the equipment, one with a full condition and one with a condition of zero. Just repair the original and you'll have two perfect copies of the single piece of equipment!

Get rid of bounty for free:
To do this you obviously need a bounty on your head. Join the Thieves Guild in Balmora at the South Wall Cornerclub. The man at the counter downstairs can take of your bounty for a price. Go outside and stand next to the crates and drop ALL of your money. Then go inside and talk to him. Discuss the 'price on your head' and agree to pay it, but since you have no money, he'll say "---- gold has been removed from your inventory." Now go outside and grab the money you dropped earlier.

Max out stats:
First you need a weapon with a constant effect that 'fortifies' any attribute, such as fortify strength or axe skill. Now equip the weapon and have it in your hand, then press and hold the X button, Left, and Right triggers all at once. Your weapon should be switching back and forth very quickly with the next and every time it does this the stat the weapon fortifies will go up. So if your weapon has 'fortify strength by 10', every time you hear the switching sound your strength will increase by 10 and stay that way, minus the 10 after you dequip the weapon, so if you buff your strength by 50 after you dequip your weapon your base strength will be +40 permanently.

This trick can also be done with the 'Bound weapon' spell. Cast the Bound spell while holding a weapon identical to the type of bound spell (for instance, a katana while casting Bound Longsword). When the weapon appears, hold X + R and your weapons will continuously switch. When the bound weapon wears off, your stat with the weapon should have increased dramatically.

Vampirism Made Easy:
To become a vampire is very simple. An easy place to go is Nerano Manor in Balmora. Go to the Nerano Ancestral Tomb and you will meet a vampire. Fight him using the Health Cheat, but don't kill him. Get bitten and then run away. Wait three days and then go to sleep. When you awaken, you will be a vampire.

You can do certain missions being a vampire and you will get boosts in certain attributes and skills. You will get 20-point boosts in Strength, Willpower, Speed, and Agility. You will get 30-point boosts in Athletics, Acrobatics, Mysticism, Illusion, and Destruction. And finally you will get 50-point boosts in Sneak, Unarmored, and Hand-to-Hand. You will also become immune to Paralysis and Common Disease and have a high resistance to normal weapons (50%). And last but not least you gain an additional 2 spells: Vampire Touch, which drains opponent's health while restoring your own, and a more potent, longer lasting version of the Levitate Spell. You still get to keep your previous spells and abilities.