I am one of five undergraduate (unpaid) summer interns for the National Legal Department of the American Civil Liberties Union (ACLU). The ACLU is a non-profit law firm and advocacy group that focuses on Constitutional law (civil rights litigation) and Human Rights advocacy. It is the largest Human Rights law firm in the world. Much like a fraternity, it is divided up into state-run affiliates (i.e. the ACLU of Kansas, or New York Civil Liberties Union-NYCLU), yet it also has a National office (which is the part I work for). The National office only handles legal cases that they feel will have an impact on the federal level. About 50-60% of our cases go to the Supreme Court, and we win a little over 50% of those (these are actually pretty good odds for a law firm). Likewise, they only take on advocacy work that will have an impact on the national and international level.
My day-to-day job involves researching legal topics, composing memos on relevant information, doing hands-on legal review (i.e. reading over sworn depositions, cataloging subpeonaed information, etc.), and assisting in the writing and editing of legal briefs and motions. This internship is a rock-solid choice for anyone who is thinking about attending law school, especially for Constitutional law, or who is interested in Human Rights advocacy (there are also advocacy-specific internships). Also, many of the State-affiliates offer their own internships, so you could do one closer to home. This specific internship is really focused on getting students ready to practice law, it's very hands-on, there are lectures every week about various facets of the law, and there are workshops on applying to law school, the LSATS, and getting clerkships and jobs. There is precious little grunt work like copying and fetch-and-carry. Furthermore, the staff are some of the friendliest, most helpful people out of any workplace I've ever been in. Truly a fantastic opportunity. Too bad it doesn't pay.