Indispensable Film Sites

The cream of the crop.

General:
Internet Movie Database - the most complete database of anything about any movie.
The Greatest Films - a critical analysis of the greatest films and more, by Tim Dirks.
All Movie Guide - an excellent database including such features as similar movies, keywords, themes, tones, and more. Along with Rottentomatoes, the best resource for finding movies you'll enjoy.
Netflix - DVD rentals by mail. Excellent selection and service. Or, if you live in California, use the superior GreenCine.

News:
Ain't It Cool News - The legendary home of more exclusive scoops and reviews than anywhere else.
Coming Soon - Updated constantly.
Dark Horizons - Another pretty decent news site.

Reviews:
Rottentomatoes - The premiere and de facto critic consensus site.
Screen It! - Content reviews along with the most consistently excellent 'quality' reviews for films of the last decade or so.

Screenwriting:
Simply Scripts - Forget Drew's Script O Rama, Simply Scripts has the largest collection of screenplay links available.
Wordplayer - A collection of columns and letters about screenwriting, covering subjects you won't find covered anywhere else, by Ted Elliot and Terry Rossio (writers of Aladdin, Pirates of the Caribbean, and more)
Screenwriters Utopia - Just about everything you could possibly want in a screenwriting site.

Box Office:
Box Office Prophets - Forecasts, summaries, analysis, humor. The most enjoyable movie-related site on the net.
Box Office Mojo - THE box office database.

Trailers:
Movie List - The one-stop source for movie trailers, old and new.
Movie Box - Another excellent site.