Buoyancy setting for players / objects

A number of interesting rooms could be created if gravity could be balanced out with a buoyancy setting.  The buoyancy setting would take a height offset number and the object/player would drift towards that height (either up or down) at a certain configurable rate.  This would allow new rooms to be created with water features, hot air balloons,  more realistic flying effects, gliders, parachutes, space stations, etc.  It would open up a huge creative void that's left by relying on gravity to only pull someone down.  

This could perhaps be a zone, like a trigger volume where the buoyancy only had effect within that zone, and only on objects with a specific tag.