Could crowd-sourced photo sharing be the future of taxonomy? Cybertaxonomy?

An artist at a Seattle hospital turned a teenage leukemia patient's room into an art installation using nearly 2,000 photos of cats solicited through social media. "In the hospital, you feel cut off," says the patient. "So the photos made me feel like I was part of the world again."

For more than 20 years, photographer James Startt has been chasing legendary cyclists in the Tour de France, capturing the fans' excitement against the backdrop of the French countryside and the raw emotion of competitive cyclists. Now, a selection of his work can be viewed online.

In 2009, two Italian photographers on assignment in Detroit kept stumbling across old photos around the city. They have compiled 200 of the photos in a book.

Their faces have weathered decades of hardship.