Whatever the reason you may decide to work with a disposable camera, here are 20 cool suggestions on how to get your camera to work exactly how you want it to. Want to make a double exposure? Smack it on your hand. Want your photos to look vintage? Damage the lens a little. Want your exposures to be colorized? Color the lens or out some clear colored tape over it.
Perhaps the coolest hack is the one that allows you to make a 3D photo? Tape two cameras together and take a photo with them at the same time. The process is a bit more complicated than the others, particularly since you have to put the photos in or photoshop the images in a stereograph to view the images together, but the result is well worth it.