Toynbee Tile resources on Flickr
There are a couple of public Toynbee Tile groups over on Flickr
: Toynbee Tiles
(13 members and 62 photos), and Toynbee Tile Detectives
(4 members and so far only 1 photo).
Doing a general search for 'Toynbee' at Flickr comes up with around 150 photos (plus around another 20 not relevant to the Tiles). Most of the Tiles are in Philadelphia but many are elsewhere, though unfortunately those posting often never mention in which city they were found.