This week's assignment for my DSLR class was to experiment with our camera's white balance settings. It is definitely worth it to take a few minutes to see if you can adjust this on your camera and how to do it. For me, I have some good presets (like Tungsten and Florescent), but my sewing space has a combination of incandescent and compact florescent light bulbs so I tried out the custom setting. This was as easy as taking a picture of a white piece of paper in the weird lighting and telling the camera to base its white balance off of that picture.
Here's the picture from my last post that I took after creating a custom white balance setting (taken without the flash):
Here is the same shot but using all of the other preset white balance settings on the camera (again without the flash)... see what a difference it makes?