Apologies if this has been posted before, but I just found this site last night and I think it's a great idea:
Geograph British Isles
Geograph British Isles
The Geograph British Isles project aims to collect a geographically representative photograph for every square kilometre of the British Isles and you can be part of it.
What is Geographing?
* It's a game - how many grid squares will you contribute?
* It's a geography project for the people
* It's a national photography project
* It's a good excuse to get out more!
* It's a free and open online community project for all