Slashdot recently posted this article on scaling and I found it just fascinating. The essential idea is that the properties of physical structures are dependent on their scale, e.g., a flea could not jump 130 times its own height if it were 1,000 times larger.
Galileo wrote about this in the 17th century, Haldane wrote a wonderful, accessible essay about it in 1928, and this fellow LaBarbera applies the principle as it relates to (some of my favorite) B-Movies.