"broken windows" : take frosted contact paper and cut it apart to look like fractured glass. The semi-transparent frosted contact paper takes on the appearance of the "glass" while the actual glass pane (which is transparent) disappears.
Mouth of Flower - Octavio Ocampo This is good art because it is an optical illusion. It could either be just some flowers with a butterfly, or you can also see a womans face. It is very creative in a subtle way.