I love when you are just travelling around through the wilderness and discover a shed or ruin. When you go inside it suddenly evolves into a big dungeon running quest. Earlier I stumbled upon a small shack and thought I'd go in to check on the owners, suddenly a bandit attacked me inside and he had a note on him revealing the house as a front for some skooma operation or something with a secret cave hidden by a bookcase. A few of the bandits were passing notes about raiding the leader's treasure room, so I took it upon myself to kill them all and take the treasure for myself.
It was a lot of fun.
Just finished solidifying Stormcloak rule in Skyrim, feels good.