Todd Howard, executive producer on Skyrim, delivered the keynote address at the 2012 DICE summit.
Within his speech he talks about how the development team did a 'Game Jam' post-development where everyone got a week to work on their own Skyrim idea....it was then put together into a video showing off all the idea....it is simply amazing some of the work.
Here is a link to the keynote address recording, the Game Jam segment starts at 20:07:
http://au.gamespot.com/shows/gamespot-l ... te20120208
As he says, any of these could appears in future DLC.....so mounted combat? spears? werebears? riding dragons? build you own house with skeletal butler? etc