Pastor Gregg has provided some excellent resources to research various missions and their goals. You may already be familiar with some of these, but the websites provide an in-depth look into the organizations, which give a better understanding of the needs and accomplishments of each of these causes.
Helpful Presbyterian Church (USA) resources:
pcusa.org, Look especially at the "News and Events" and "U.S. and World Mission" tabs. Through the website you can also sign up for an electronic or print version of "Presbyterians Today" magazine.
Learning about persecuted Christians: The Voice of the Martyrs at persecution.com
Christian Relief Agencies, each of which will provide information and resources for the great needs of our world and how Christians are going about meeting those needs:
World Vision: worldvision.org
Samaritan's Purse: samaritanspurse.org
Compassion International: compassion.com
Heifer Project International: heifer.org