I found this design to be cool and functional.
10 percent of all the electricity used in Europe in 2006 is consumed by street lighting. This is equal to 2,000 billion KWh, and resulting in 2,900 million ton of carbon emissions.
The solar tree design went on display for four weeks in October on a busy street in Vienna, Austria. They were able to provide enough light during the night-time even when the sun did not show for as much as four days in a row.
from link: metaefficient