The U.S. State Department provides several opportunities for students of numerous majors from Political Science to Engineering. There are two categories: Domestic and Overseas. Each has its own programs and benefits. Both are unpaid internships, unless the applicant shows a need in their application.
The Overseas Internships allow students to work in U.S. embassies and consulates all over the world. Housing is often found at no cost to the interns.
The Domestic Internships are generally in Washington D.C., although there are a few other opportunities. Transportation in D.C. is paid for, but the intern must provide their own housing.
Interns work in the offices "write reports on human rights issues, assist with trade negotiations, assist with citizen's services..., help Americans in distress abroad, or organize conferences or visits of high-level officials." There are also opportunities to meet with senior level officials in the State Department and some social activities.
State Department Careers Site: