Photograms (which I've described in more detail in this answer) involve placing objects in direct contact with a photosensitive surface, usually outside a camera. Film is perfect for photograms for a number of reasons:
- It's cheap
- It's disposable
- It's available in large sizes
- It's easy to use outside of a camera
Digital camera sensors fail on all four counts!
My father-in-law produces photogram-like images by capturing light refraction patterns with a lens-less film SLR body. In theory you could do this digitally too and we've discussed it a few times, but I'm always reluctant to expose my camera's sensor to the elements so routinely. Again, film just doesn't have that issue.