Looking back one, two and five years ago today (give or take!) on Worldchanging:

2009
The Backstory of Stuff: New Sites Enable More Transparency in the Supply Chain
Kirstin Butler explores the increased accessibility of online mapping tools and wiki-style collaborations have changed the cartography of consumption.

2008
One Planet, Three Decades
A classic Worldchanging essay by Alex Steffen in which he discusses what it really means to "be the change"...

2005
Narrowband - one solution for African connectivity
Ethan Zuckerman reports on Arrow Networks, a Ghanaian company that is building a national wireless data network that can provide modem-speed or better data connections at low cost, over long distances, without line of sight...

Other recent "look backs":
September 15
September 16
September 17