Looking back one, two and five years ago today on Worldchanging:

2009
For The Love Of Water: H209 & The New Generation Competition
Sean Conroe reviews the top three prize winners in The New Generation Competition, s challenge to undergraduate students in the U.S. and the Netherlands to submit their own ideas for improving water systems...

2008
Conceptualizing the One Planet City
Holly Pearson discusses the work city planning PhD candidate Jennie Moore is doing at the University of British Columbia on conceptualizing the "one planet city"...

2005
Africa: Whatever You Think, Think Again
Nicole-Anne Boyer reflects on the National Geographic magazine special issue on Africa and says that it brought her attention back to this continent in a fresh way...

Other recent "look backs":
September 6
September 7
September 8