First, I applied rope trim around the molding to give a touch of color and finish off the edges. Rope trim is a wonderful way to add definition between contrasting paint colors in older houses where walls and ceilings aren't straight. Then in each corner I applied a decorative onlay - easily glued on, spackled and painted the same white as the rest of the ceiling.
Here is the before...(this picture was taken before I painted the ceiling border the in the wall color)
I am very pleased with the results. Actually, doing the ceiling was easy; the hard part was trying to take these pictures! (I so want a wide angle lens) I hope you like it and it has inspired you to do something creative with your, "fifth wall": your ceiling.