Celtx

Celtx has an industry standard SCREENPLAY and an International THEATRE editor. Each has all of the features writers need to keep their fingers moving, like intuitive formatting, text auto-complete, pagination, script styles, CAPS selection, scene management, spellchecker, embedded notes, find and replace, and PDF generation. Celtx also includes a plain text editor so you can pen a poem, compose some lyrics or write a short story.

Drews Script-o-Rama:

Download and read scripts for several recent hit movies.

http://www.script-o-rama.com/table.shtml 

Screenwriters Utopia

Read articles about screenwriting by renowned professors, as well as reviews of screenplays, participate in chat rooms, read interviews with screenwriters, etc.

http://www.screenwritersutopia.com 

Charles Deemers Screenwriters Homepage

Screenwriting and playwriting basics from a professor.

http://www.geocities.com/cdeemer/ 

Screentalk

A variety of resources, articles, and bulletin boards for aspiring screenwriters.

http://www.screentalk.biz/ 

http://www.joblo.com/moviescripts.php

Internet Script Database

http://www.iscriptdb.com/

More Scripts

http://www.simplyscripts.com/

Free Screenwriting Software

http://breakingin.net/freebies.htm

Screenplay Search Engine

http://www.rosebud.com.br/newscripts/menu_movie_scripts_and_screenplays.htm