The Association of Community Organizations for Reform Now (ACORN) is a grassroots political organization that grew out of George Wiley's National Welfare Rights Organization (NWRO), whose members in the late 1960s and early 70s invaded welfare offices across the U.S. -- often violently -- bullying social workers and loudly demanding every penny to which the law "entitled" them. In the late 1960s, ACORN co-founder Wade Rathke was a NWRO organizer and a protegé of Wiley. Rathke also organized draft resistance for the militant group Students for a Democratic Society (SDS) during the same period.
A very interesting read on the history of Acorn/obama.