Here are some of mine that i found:
http://www.youtube.com/watch?v=OLgrFUiXqoE
http://www.youtube.com/watch?v=UzoiqNkyNF0
http://www.youtube.com/watch?v=H5kIzo2LbbQ
http://www.youtube.com/watch?v=Ope5Kj32KHU&feature=plcp
http://www.youtube.com/watch?v=mEpFP31OZk4&feature=plcp
I don't know if this has happened to anyone else but, I jumped off of a building in whiterun and i landed under the city somehow. I kept walking past the gate and literally walked under most of the entire map of skyrim. I got it to happen a second time but haven't gotten it to work since. :P