This park pavilion designed by Jiyeon Song uses a complex arrangement of perforations to display different lines of a poem in its own shadow throughout the year. From the site:

Using a complex array of perforations, the pavilion’s surface allows light to pass through creating shifting patterns, which-during specific times of the year-transform into the legible text of a poem. The specific arrangements of the perforations reveal different shadow-poems according to the solar calendar: a theme of new-life during the summer solstice, a reflection on the passing of time at the period of the winter solstice.

Jiyeon’s site about the project appears to be temporarily down, but I’m told there are some awesome videos there of the construction and development of this project. Via Geekologie.