I have two, first I was sent on a quest by a fellow companion to hunt down a dangerous woman who has escaped from jail. I finally tracked her down outside of Whiterun only to discover that she had apparently had a six change and was now a wanted man instead.

The second is more curious however. I entered the town south of Dragons Reach, the one with the love triangle between the bard, elf and shopkeepers sister. The elf lay dead in the street, a mysterious crime to say the least. I promptly relieved his corpse of his house key and then went and perused his house for valuables. Two weeks later while in the forest I was attacked by three mercenary's. After killing the mercs and checking their bodies I found a note signed by the elf who had hired the mercs, it was the dead elf. He had hired the mercs because I had stole from him, apparently even from beyond the grave elves hate it when you ransack their house.