American Film Institute (AFI): A great website for cinematic criticism and commentary.
Internet Movie Database: Provides cast biographies, reviews, and plot overviews.
MRQE: The Movie Review Query Engine: The continually growing site provides a searchable index of all published and available reviews, news, interviews, and other materials associated with specific movies.
New York Times Movies: A great resource for film reviews and criticism from the pages of the New York Times, including trailers to new films.
RogerEbert.com: A site dedicated to the life's work of the late film critic Robert Ebert. The site continues to add movie criticism, commentary and community content.
Rotten Tomatoes: Includes film reviews from the critics and regular audience members.
Filmsite's Film Reviews: Reviews include a prominent movie poster, historical background for the film, a summary or synopsis of the film, excerpted dialogue, and critical commentary in order to appreciate the film more fully.