My house - very sensibly given its age! - was built with a piece of copper central heating pipe in the wall from the loft to the living room, which was used as a duct for the TV downlead. It's now crammed full of other wires (To get any more wires in I'll have to remove the TV lead, which is harmless as I don't watch TV.)

So ... any housebuilders reading this, put ducting in the wall, not wires!