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

2009
Transparency, Accountability and the "dot eco" Debate
Peter ter Weeme reports on the Internet Corporation for Assigned Names and Numbers idea to introduce a new top-level domain like .eco, which, like the practice of eco-labeling, could provide one more tool to help consumers make good, green choices online...

2008
Money Makes Way For Happiness, But Happiness Still Can't Be Bought
Samantha Cleaver examines happiness and the ways we could adjust our happiness baseline to increase our happiness in the absence of increasing monetary wealth...

2005
Retro: Urban Sustainability, Mega-City Leapfrogging
Jamais Cascio recommends a classic post by Alex Steffen's on the future of cities...

Other recent "look backs":
August 20
August 23
August 24