This is an excellent overview of using flickr in non profits and for individual use.

How to do you explain flickr to those who haven’t heard of it?

Flickr is a web-based digital photo sharing application that uses tags to facilitate finding people and photos. It isn’t simply about putting your photos up on the web for the world to see. What if you could invite other people from the around the world to have discussions about those images? What if you and your colleagues could annotiate these photos with your own descrptions and observations? What if you could become part of an online community that contributes images of similar topics for you to consume? And, what if you could subscribe to an RSS feed so anytime a new picture was added about a topic you care about, were studying, or writing about – it would come automatically to you?