First you must complete the Dark Brotherhood quests up until you receive Shadowmare as a reward. Shadowmare is special in that he cannot be killed (only knocked unconscious). Knock Shadowmare unconscious (you don’t need to be quick about it, he won’t fight back). As soon as he drops, you are given the option to access his body via the spacebar. Open him up and dump your extra junk into him (open him then go to your inventory button and single click items to move them over). Shadowmare will pop back up after a few seconds, and you’ll both be good to go.

Whenever you need to access your gear, simply knock him out again. I’ve used this trick for a while, and it appears that Shadowmare has no weight limit, and items remain forever. This trick won’t work on normal horses because they die (and ~ resurrect clears their inventory).

Sometimes after Shadowmare wakes up, he begins to slowly walk away, to stop this, jump on him and quick transport to a location; this fixes him. Also, be careful not to get onto a regular horse, this messes up your “tie” to Shadowmare, and is a good way to accidentally lose him (not sure where he defaults to).

First, goto the Imperial City Talos Plaza District. Then, open your map (the one that shows the names of all the buildings in your current location), and find Dorian's house. Go inside his house and bribe him all the money you can, then make him upset by making disposition going down by playing the disposition mini game, and repeat the bribing process. Once you've bribed him a good amount of money, such as 1000 Gold, kill him as fast as you can.

A good way to kill him without allowing him to run away is to push him in the other room and stand in the doorway while attacking him. After he's dead, goto his body and keep clicking on his gold. DO NOT select "Take All" as it will ruin the glitch, just keep clicking his gold. You'll get the amount of gold he has on his body every time you click it, and he will never run out of it.

(Origional release version)
At the very end of the quest to cure Vampirism, the count of Skingrad (the last person talked to in the quest) will reward you (if you are a full vampire, or not) with 1,000 gold (or more depending on your level).
If you continue again to click on the message that asks about a reward, he will keep giving 1,000 gold.

First you need a bow, some arrows, and the item you wish to duplicate. Using this will allow you to duplicate as many items as the number of items in your quiver.

First take out your bow and equip some arrows. Pull back the arrow but do not fire it. Press tab and double click on the arrows you currently have equiped. Then shift click the item you wish to duplicate. Once you exit out the menu the item would drop but it will be the same amount of items as your arrow. To better help yourself duplicate things it is advised to have a couple of the item you wish to duplicate so that you can pick them up faster if you have a ton of arrows. This trick works well with things that weigh very little but are great in value such as soul gems and jewelry.

First you need to get the Thieves Guild quest "Boots of Springheel Jack" and complete the majority of the quest, retrieving the Boots. Do not, however, return the boots to the Grey Fox.

Upon obtaining the Boots, equip them to get a +50 Acrobatics bonus, then travel to the Shrine of Sanguine and begin the Daedric Quest there. Follow through that quest, and allow yourself to be arrested by Leyawiin guards when they try. All your possesions will be taken, except for key items (which include the Boots).

Stay your time in jail, and upon exiting, check your inventory. You should still possess the boots, but when you try to equip them the game will tell you "You cannot equip this item at this time". However, if you check your current enhancements, the +50 to Acrobatics will still be there! You can now wear other footwear, but still have the bonus from the Boots of Springheel Jack!