Various listings from Idealist

Some great ones below

Economic Policy Program Internship
German Marshall Fund of the United States
http://www.idealist.org/en/internship/130704-160
Washington, District of Columbia, United States

Jubilee USA Grassroots Internship
Jubilee USA Network
http://www.idealist.org/en/internship/130707-260
Washington, District of Columbia, United States

Fundraising and Development Internship
Government Accountability Project
http://www.idealist.org/en/internship/130718-30
Washington, District of Columbia, United States

Global Youth Network Intern
ActionAid International USA
http://www.idealist.org/en/internship/130715-263
Washington, District of Columbia, United States

Apply to Jubilee USA's Communications & Advocacy Internship Program
Jubilee USA Network
http://www.idealist.org/en/internship/130706-226
Washington, District of Columbia, United States

Education Intern
The Alliance to Save Energy
http://www.idealist.org/en/internship/130768-313
Washington, District of Columbia, United States