Jon Beer's latest article in the Trout & Salmon mentioned the following web-site
Geograph Britain and Ireland - photograph every grid square!
I loaded it up and it is very interesting indeed. You can type in at the top right corner a postcode or description and it opens all photos taken in the area. I think it finds all those with OS grid references and maps them to their database. What is really interesting is you can enter say “river Dee at Park”, open a photo and a small ordinance survey map appears. One can then follow the river using the N,S,E,W compass points and as you do it photos taken in that area appear. Terrific for looking at new waters
When you have the small map you can also click the interactive link below and it opens up a full map of the area with dots highlighting all the photos taken. You then click on any of these to open the phot up.