Isaac Kehimkar's entire Flickr photostream is devoted to butterflies, because he's an "ardent butterfly lover".
posted by bwg on Feb 7, 2011 - 20 comments

While many quirky news buffs may be aware of the story of Phineas Gage -- the Vermont railroad foreman who had a three foot iron rod penetrate his skull as the result of an explosion and lived to tell about it -- fewer know that the only known photograph of him was recently discovered. Fewer still know that the identification of that photograph happened via a Flickr comment. (no thanks to you LA Times, previously) [more inside]
posted by jessamyn on Jul 29, 2009 - 77 comments

Michael Hughes takes cheap souvenirs, and then takes photographs with them superimposed over the real thing. A Flickr photo set.
via Wired's Table of Malcontents
posted by Bugbread on Nov 17, 2006 - 30 comments

Bird Watchers Guide on Flickr. "Linked list of species submitted; find all photos of a species here".
posted by nthdegx on Jun 5, 2005 - 11 comments