From the Harvard Gazette, an article on Unitarian minister and abolitionist Charles Follen, and the story of how he promoted the Christmas tree.
http://www.news.harvard.edu/gazette/1996/12.12/ProfessorBrough.html
Catholic Encyclopedia article on this body of doctrine held by one of the Antitrinitarian sects that gave rise to Unitarianism.
http://www.newadvent.org/cathen/14113a.htm
English General Baptists are now, for all intents and purposes, a part of the Unitarian movement. This site illustrates the adoption by the General Baptists the doctrines of unitarianism and universalism (though this convergence has nothing to do with a similar convergence in the United States) in the first quarter of the nineteenth century.
http://www.uuchristian.org/egb/
Annotated list of science fiction novels and stories with UU characters or references. Also, UU authors of science fiction.
http://www.adherents.com/lit/sf_uu.html
An analysis by J. Meacham, Unitarian Universalist minister, of both 1893 and 1993 participation by Unitarian Universalists in the Parliament of the World's Religions.
http://www.jlc.net/~jmeacham/parliament.html