The opposite inset VERY USEFUL

When you are working with the subd surface and you want to create an inset as a support edge loop:

• Select the surface loop that you want to inset.
• Press O (letter)
  This will create an edge loop to the surfaces that are connected to the selected surface.

You can flip the inset direction by pressing ) again, in case you don't want to place edge loops to the connected surfaces.

Then if you want, you can press I again and inset the selected surface loop as well. This way both of the surfaces will have the supporting edge loops.