I find that most people who share their photographs on Flickr are very generous. I found this out when looking for images from a temporary exhibition a few years ago which I needed for a paper. I had completely failed to manage to find anything suitable via the museum, but did turn up some great photographs of the display on Flickr. A quick email to the photographers resulted in permission to use their work. Marvellous!
The Commons is a Flickr-venture in partnership with museums and collecting institutions worldwide. The idea is that museums, galleries and archives share their photographic collections online in return for users' knowledge and expertise. The majority of institutions taking part are US-based, but there are some UK museums represented. Among my favourites are the National Media Museum's photostream. I love the circular Kodak prints and the spirit photographs.
What will you find?