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

2009
Wanderlusting No. 3: Lego Power
Chris Turner writes a postcard from Legoland and commends the Danes for their inspiring tableau on energy infrastructure...

2008
Eric Lombardi's Zero Waste Park
Julia Levitt reports on the Zero-Waste Park conceived by Eric Lombardi, the waste-management guru behind Boulder, Colo-base recycler Eco-Cycle...

2005
Retro: Ethan Zuckerman -- the WorldChanging Interview
Alex Steffen shares an interview with Ethan Zuckerman and says that it has a special place in his heart for a few reasons...

Other recent "look backs":
August 19
August 20
August 23