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

2009
Worldchanging Essay: Creating Responsible Voluntourism
Carissa Bluestone explores voluntourism - "planning a vacation to include short-term charitable work" - and debates its effectiveness...

2008
Museum of Jurassic Technology
Regine Debatty reviews David Wilson's Museum of Jurassic Technology, a place where the boundaries between history and fiction, magic and reason, narrative and scientific method are in fact completely fluid...

2005
Ribbons, Sheets and the Nanofuture
Jamais Cascio reports on what he thinks is arguably the biggest technological breakthrough of the decade...

Other recent "look backs":
August 16
August 17
August 18