Replace objects

We have Data link/transfer but we don't have something which can replace an object (say mesh) with another (say a Light or a empty or a curve). As it stands it's only possible to mass replace stuff if it's mesh to mesh, not empty to lights or empties to mesh. A modifier or tool which basically just hides/deletes the applied to object and adds a copy of a selected object over where it would be immensely useful.