None.
Through modding though, I had more weapons, more homes, larger landmasses, etc.
Well there's the Hearthfire DLC that lets you build houses and adopt children. I believe you can get up to three plots of land with three houses. You build them from scratch having to buy or find supplies. The children you adopt can bring you special items from time to time.
There's the Dawnguard add on which adds more places to explore and you choose sides between the Dawnguard which are Vampire hunters or becoming a Vampire. (I chose to become a vampire, the quest line is really cool. And you can cure vampirism) This add on brings a whole new amount of weapons, armor, magic and abilities for vampires and werewolfs.
Finally there's the Dragonborn add on. This adds another world to explore, it's a large island called Solsthiem. The Black Books are here which is a whole new quest line and can give you really cool abilities. The best part of the quest line is getting the ability to ride on the backs of dragons.