Just a small note for the users of Manfrotto 190 tripods with removable center columns.
The 556B center column is available as an accessory for these - it allows you to add the capability of levelling the head separately from the orientation of the legs. This means that if you are using a video head it can start movement dead level with the horizon and then move to a smooth pan. You'll see a mechanism like this on the larger professional motion picture tripods.
The basic platform sits in a bowl and you get some 15º if tilt in all directions - the grip down at the bottom of the column then tightens up.
What it would also be perfect for is the panorama enthusiast. Combine this leveller with a simple turntable and you would have a complete light pano head that doesn't flop around. Gotta be a good idea for someone.
