If you have DVD-player software you could do worse than getting hold of a THX-1138-qualified DVD. They usually come with some sort of calibration utility for setting up the brightness, contrast, and colour. I'm not going to claim it's ideal for a monitor, but it may be a practical low-cost standard to work from. "Pearl Harbor" is one film with that feature, but I wouldn't recommend buying the DVD for any other reason. "Lord of the Rings" isn't THX-1138, but the range of lighting in the scenes is an excellent test -- "Fellowship of the Ring" has both snowfields and dark caves, and getting both to look good is a good target.