The Luminous Landscape has an interesting article about modifying a DSLR to only pic up the infrared portion of the light spectrum. Of course, doing this will not only cost you US $450, it renders your camera unable to do any other type of photography.
Oh, and it does not turn out quite like the picture here, either. While this is a cool effect, the end result is much more black and white.
So, don't get your hopes up to high unless you have an extra DSLR just sitting around. Here is the article.