Royal Journal, an excellent collection of found photographs, notes, &c., sadly defunct, has been resurrected as a fine photoblog, Pic Patrol. [Alas, it appears to be defunct yet again (June 29).]

Satan's Laundromat, actually another fine photoblog with bite (see the entry "Red America").

From here in Chicago: Big Happy Funhouse, a great and often hilarious weblog of found photos.

Time Tales is a found photography project by two Dutch photographers. It also has a wonderful page of links to an eclectic collection of interesting websites.

Object Not Found, an Australian collection of found photography and writing, has been re-designed and updated after a hiatus.

Is This You? is a collection of photographs & IDs found around London; sometimes, the photographs manager to find their way back to where they came from. Doubly found, as it were.

Look at Me, a found photography project by the La Modern Association art collective. The website regularly links to interesting art (this rather stunning panorama of Paris by night, for example) and art-related news found on the web.

Found Magazine, the website of the eponymous zine dedicated to found objects: photography, writing, even audio. Founded by This American Life (my favourite show on radio) contributor Davy Rothbart.

Not quite found objects, but found stories: Other People's Stories. It hasn't been updated for a while, but the archives are well worth perusal.