Here's one of my favorite uses of empties:
In the Philippines, the used bottle issue doesn't involve intruders, but poverty and darkness. Millions of homes are without electricity and daytime darkness is commonplace. Using an appropriate technology innovation from MIT students, MyShelter Foundation has launched its Isang Litrong Liwanag (A Liter of Light) campaign that converts discarded bottles into stunningly elegant solar bottle bulbs.
In a nutshell, a one-liter bottle is filled with a water and bleach solution, sealed, then secured in the roof of a home, school, or warehouse with no electricity. A simple hole in the roof would admit rainwater and a mere shaft of light. Not very useful. The solar bulb, though, emits light in all directions.
Hell, I have electricity and I'm mulling over the idea of installing a few — in the garage, a tool shed, wherever.
From Liter of Light's tumblr post:
MyShelter Foundation has spearheaded a daunting project. Through the “Isang Litrong Liwanag” (A Liter of Light) campaign, the foundation seeks to provide sustainable lighting to a million households by 2012.For more about MyShelter Foundation and the Liter of Light campaign (with more images and video), see its website.