According to Wikipedia, contact sheets are "a photographic image produced from film; sometimes from a film negative, and sometimes from a film positive. The defining characteristic of a contact print is that the photographic result is made by exposing through the film negative or positive, onto a light sensitive material that is pressed tightly to the film."
*just a note* not all things on Wikipedia are correct, but it is a useful source of information, as long as you are sure it is the correct useful information that you need.
Below is a scan from a contact sheet of some shots I did of my mom, I like how keeping the contact sheet border adds a certain nostalgic quality and frames each image. As well, since the scanner wasn't the best scanner, added lines and imperfections to the image. I might start doing this for any image that correspond to each other. It will be an interesting practice piece. I notice on Adobe that they have a tutorial to make a contact sheet, but that is more for organization. What I will try is keeping the frame part, and replacing the images...we'll see how it goes.
found this cool link on flicker to someone taking the contact sheet to be the actual photo itself, pretty cool idea. I'm always impressed how people come up with new and interesting ways to see things. And maybe it's NOT new, but it's new to them.