Here is an interesting tutorial to create Through the Viewfinder photography:

http://www.squidoo.com/-how-to-create-do-take-through-the-viewfinder-photographs-ttv-photography-tutorials-instructions

This is a link to some really nice photographs by Cassie Beck made using this technique:

http://www.etsy.com/shop/CassiaBeck?ref=seller_info

Here is an image shot in class with a Canon Rebel and a small viewfinder Brownie.
viewfinder-class-portrait.jpg



Here is the picture I (Emilie) took during the pin hole experiments.
DSC02771.JPG
Below is the same image, inverted with auto contrast applied in photoshop:
pinhole_emilie_positive.JPG