There's an excellent post on the subject, here. (Inspired by Jonah Goldberg and his recently published book, Liberal Fascism.) [UPDATE (02/11/08): See also this, by Thomas Sowell.]
Related posts at Liberty Corner include:
"Calling a Nazi a Nazi" (12 Mar 2006)
"Things to Come" (27 Jun 2007)
"FDR and Fascism" (30 Sep 2007)
"A Political Compass: Locating the United States" (13 Nov 2007)
"The Modern Presidency: A Tour of American History since 1900" (01 Dec 2007)
"Intellectuals and Capitalism" (15 Jan 2008)
"Political Correctness" (29 Jan 2008)
"The People's Romance" (30 Jan 2008)
"Fascism" (30 Jan 2008)