A big trend lately to spice up interior doors has been to paint them - surprise, surprise - black.
For the cost of a can of paint and only a few minutes of actual work, you can completely change the look and feel of your space.
Here are some before shots of my doors, in a series of poor quality iPhone pictures:
Bland, boring, blah. A quick Google or Pinterest search will reveal a world of inspiration, but here are some photos that inspired me:
(celebrity designer Nate Berkus' office)
I even decided to paint over the hinges with some gold paint I had around - they were covered in several layers of white paint anyway. If you're going to paint hinges just be sure to give the door a full motion swing immediately after you paint, and even a few times while it is drying to ensure the hinges will continue to work smoothly.
I also decided to switch out that terrible, builder-basic brushed steel doorknob for a simple brass doorknob. Looks great next to the brass faceplate solution I applied to the light switch a while back.