I found this one at Treehugger. Everyone has at one time or another seen footage of derelict airplanes stored in the western deserts of the United States. The planes are scavenged for their more valuable electronic parts but leaving the airplane fuselages to clutter the desert.
Well it appears that some green minded architects in New York have thought of an interesting new function for these abandoned tubes of aluminum and steel. They want to use them as the primary structural component of a new library in Guadalajara Mexico.
How cool is that!