I have gotten a lot of positive feedback about some of the silly "multiple exposure" shots I did lately, and a couple of people have asked for a tutorial, so here it is!
Set up your digital camera on a very secure tripod. When taking the shots, don't let it move at all when you press the button. Even being off by a fraction is noticeable when you try to stitch the shots together!
Put the images in an image editing program, and take half of the behind image and paste it over the front image.
Isolate the part of the image that overlaps using the lasso tool.
Erase the part of the image that overlaps.
Paying careful attention to shadows and reflections, erase either the foreground or background image in places until they look seamless. Repeat until you have enough layers on, and then flatten the image and adjust the brightness/contrast and apply any filters.
The finished product: Voila!
If anyone tries this, please comment here with a link to your post!