Ring Of Increased Carry Weight
As we've noted, carrying capacity is extremely important in Skyrim. If you have a ton of space, you can accumulate a ton of loot to use or sell. If you don't, you might have to leave an item behind in order to make it back to town.
If you don't ever want to think about carry weight again, take a look at this simple mod. Ring Of Increased Carry Weight delivers one ring that adds 1000 points of extra carry weight and another that adds 1000000 carry weight.
The rings are 200 gold and they can be purchased from the well-known Belethor's General Goods in Whiterun.