“Today, Flickr and TechSoup announced a partnership, Flickr for Good, to offer 1-year Flickr Pro accounts in quantities of two or five accounts for eligible non-profit organizations. These accounts allow unlimited storage, photos up to 10 MB in size, organization into any number of sets and collections of sets, and submission into the pools of up to 60 Flickr groups.”
Read about it here:
PS: Thanks Sarah!
Addendum: Be sure to read Sarah's comments below about public library eligibility. :)