Typical hollow core doors are cheap, and look cheap. You can get the look of a beautiful panalled door with just a small investment in paint and plywood.
Jenna Sue details this impressive makeover on her blog and says that it's a very easy project: Measure and cut the plywood for the panelling and secure it with a nail gun. Repeat on the other side. After some sanding and a couple of coats of paint, you've got an updated, richer looking door.
Jenna Sue's entire home is lovely, so you might want to take a look at that too here and her other DIY projects for more inspiration.