Jail Finds is a flickr set of art found stuffed inside books by the account holder at the jail where they are a volunteer running the book cart.
posted by jonson on Oct 29, 2007 - 9 comments

The Box Doodle Project - Cool cardboard art.
posted by dobbs on Jul 19, 2004 - 3 comments

The Museum of Bad Art
posted by anastasiav on Mar 15, 2004 - 10 comments

Stickernation - found sticker art from around the world.
posted by dobbs on Jan 27, 2004 - 5 comments

TRASHLOG — or — arresting and acute observation of ordinary offal.
posted by pedantic on Jan 23, 2004 - 5 comments

Time Tales : a collection of abandoned photographs, found at fleamarkets, thriftshops, or just lying on the street
posted by anastasiav on Nov 15, 2003 - 7 comments

Object Not Found. Lost and found photographs, postcards and letters.'The collection of postcards, photographs and letters collected here allows me to peek into a however small part of other peoples lives. '
Found via Countries of the Mind, a page about an imaginary world, and its postage stamps and postcards.
Related interest :- P22 Mail Art, and gallery.
posted by plep on May 22, 2003 - 5 comments

StreetMattress.com - Much like "found art", this site chronicles the phenomenon of abandoned mattresses, and finally gives the public a forum on which to comment on them. Some if my favorites are here, here, and here.
posted by emptybowl on Jun 11, 2002 - 10 comments