As more and more people use online photo sharing tools, they could be an effective way to promote library and library resources. Have a look at this library slide show in Flickr . I use Flickr to create two photo galleries. All the pictures that were tagged with Computer in Libraries 2008 and libraries from Flickr show in my blog.
Here are some of the libraries and library associations that have presences on Flickr:
Abilene Public Library
Boston Public Library
Library of Congress
University of Vermont
Waukee Public Library
Yale Science Libraries
I believe there are much more out there.