Instead of just looking at the websites for Amnesty International, Doctors without Borders, and Oxfam, why not check out some books that have been written about these organizations?
Keepers of the Flame : Understanding Amnesty International, by Stephen Hopgood. 2006.
Diplomacy of Conscience : Amnesty International and Changing Human Rights Norms, by Ann Marie Clark. 2001.
Like Water on Stone : the Story of Amnesty International, by Jonathan Power. 2001.
A Cause for Our Times : Oxfam : the First 50 Years, by Maggie Black, 1992.
Bridge of People: a Personal View of Oxfam’s First Forty Years, by Ben Whitaker, 1983.
Hope in Hell : Inside the World of Doctors Without Borders, by Dan Bortolotti, 2006.