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

2009
Are You a Vegetarian, or Just Vegcurious?
Sarah Kuck explores some of the different ways people are changing their diets away from high-planetary-impact meat-based diets...

2008
Mapping the World's Renewable Energy Potential
Sarah Kuck reports on 3TIER's new maps that help renewable energy investors save money and optimize power by better forecasting weather and climate information for wind power and solar gain...

2005
The End of Oil
Jamais Cascio reviews Paul Roberts' book "The End of Oil" and puts peak oil doom into perspective...

Other recent "look backs":
August 2
August 3
August 4