A couple of you asked how to do the"ghost" picture. It involves multiple exposures and a reeeally steady tripod.
1. Set your camera to do a multiple exposure, ie. don't advance the film between the first and second shot.
2. Find the correct exposure setting for your scene. The divide the settings in half and set your camera accordingly. By doing half the expsoure time in each shot, you end up with one correctly exposed picture.
3. Take a picture of the scene, sans "ghost".
4. Take your second shot, being very careful not to move the camera. This time, add what ever the ghost is: a person walking past the camera, an object added to the landscape, whatever.
When the film is developed, you'll have a semi-transparent image of whatever you added to the second shot. Enjoy!