Easy level ups/cheats

Easy Speech skill
Go to Riften, and talk to the Dark Elf named Ungrien. Choose the "Tell me about Maven Black-Briar." option, and then select the persuade option. After that, the persuade option will not disappear, allowing you to keep selecting it as many times as desired to get easy experience and max out your Speech skill. Note: This glitch was done on an unpatched version of the game. You can delete all patches for the game by using the "Clear hard drive cache" code for the Xbox 360.
free training
Get any skill trainer as your follower, and train your skills with him. Then, ask him to trade, and take the gold you gave him back.
To get costly (especially on later levels) training for free, enter any guild where there are trainers in what you need, and gain their trust. Get the desired training you need from the trainer, and then pickpocket him (your money for the training will be in his pocket). It would normally be considered a crime, but the guild will not do anything about it or report it.
Getting items from display cases without lockpicks
This trick works on any item within a locked display case. Look directly at the item through the display case glass, then press A to activate the lockpick mini-game. Instead of actually picking the lock, press B to exit the lockpicking screen, then immediately press A. If done correctly, you will take the item from within the case without having to unlock the display case. For example, you can use this trick on the Elven Sword in the display case in Jarl Balgruuf's bed chamber area in Dragonsreach. It has a Master level lock, but this trick allows you to get it without even picking the lock. Note: This is still considered stealing in most cases; thus, try not to get caught.
Restocking any merchant's items and gold
To instantly refill any merchant's stock and gold, simply sell or buy anything from them. Then, save the game, kill the merchant, and load the saved game.
(not a cheat)
Becoming a werewolf (lycanthropy)
There are several benefits to becoming a werewolf. In human form, you have increased health. In werewolf form, your speed and physical strength are increased. You are able to travel faster, have claws to tear enemies apart, and can use your howl to scare enemies to run away from battle. When you get injured, you can feed on ravaged corpses as a werewolf to heal your wounds. The werewolf effect is only temporary, and you ultimately revert back to human form, but you can prolong this effect. As a werewolf, you can also avoid the rested buff from sleeping. To become a werewolf, follow the questline of The Companions Of Whiterun. Once you reach the "Silver Hand" quest, you will take part in a secret ritual, where you drink another werewolf's blood and turn into a werewolf yourself. You will be given a choice to commit yourself, and the quest will not advance if you do not commit.