I've recently discovered the beauty of raw image files taken with a digital camera. The .nef files (It appears that in the future the standard raw image format is going to be .dng.) that my camera can save are essentially digital negatives unlike the .jpegs most cameras save images as. Because jpegs are compressed the image quality is degraded and your ability to adjust elements of the photo are severely limited. A raw image file does away with that and software such as Apple's "Aperture" or Adobe's "Lightroom" are built to work with raw images the way one would work with a negative in a darkroom.

I didn't have very many images on my computer that I had taken in .nef format but here are a couple that I have that I've tinkered with a little bit.

Read more about it here.