Cheap door with paint can make it prettier! DIY: Upgrade A Door With Molding - if your interior doors are blah, this tutorial will show you how to add inexpensive moulding & paint to your existing doors.
Adding Molding and paint to brown FLAT plain interior doors (jen's note: sure it's cheap to just buy new white hollow core doors, but then u lose all the insulating powers of those original heavy solid doors.
I love the penny tile back there. To make "custom" glass kitchen cabinet doors, just pry off the back wood part, have a piece of glass cut at the hardware store, attach with a heavy duty clear caulk. She used penny tile on the back of the cabinet.
Jenna Sue: Master Makeover: DIY Plain to Paneled Door. remove door, sand, make paneling using plywood. Nail, covered nail holes, add hole for door nob + paint. She removed door and adjusted door casing.