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

2009
The Cruel Cost of Clunkers
Suzie Boss reports on the hidden social cost of maintaining clunker cars and how one innovative non-profit, Bonnie CLAC, is working to improve the lives of low-income families by getting them reliable, fuel-efficient vehicles...

2009
Free Data. Big Picture. Very Cool.
Which countries are healthiest, wealthiest and most educated? The Gapminder knows...

2005
The Human Storm
Jon Lebkowsky reflects on the social chaos of Hurricane Katrina's aftermath and the painful lessons the storm and the human response to it, can teach us about the kinds of planning and preparation needed to respond to future catastrophic 21st century weather events...

Other recent "look backs":
August 30
August 31
September 1