Story Development

Various Movie Scripts/Screenplays can be found at www.movie-page.com (A - M) (N - Z) or www.simplyscripts.com.
Celtx is a very nice editing tool for writing scripts, etc.
Nice overviews on what is a treatment and how to write one can be found at www.writingtreatments.com resp. www.wordplay.com.
Accurate predictive analysis of the Box Office value of film scripts:

Glossary

Treatment: A treatment is a full exploration of a story. Covers character, plot, setting, theme; clarifies the intent of the writer. Can contain character descriptions, a synopsis, or statements on theme and tone. Attempts to convey the filmgoing experience through to the story's end; may use bits of key dialog. Usually more than three pages; average is seven to twelve. My personal feeling is that when a treatment goes past 30 pages (and some can be 80 or more, and include sections of screenplay) a writer might just as well show the finished script. By design, I think, a treatment should be less detailed to read and write than the script, or what's the point? (This is a presentation note only -- I think it's a fine technique as a writer to simply let the treatment keep building until suddenly you have a script on your hands.) (Wordplay)
Story Outline: An outline or story outline is sometimes used interchangeably with synopsis -- but in fact they're almost always a bit longer, with more detail, more emphasis on character, tone, and theme, and not solely plot-driven. (Wordplay)
Synopsis: A synopsis can be one long paragraph, or several paragraphs; probably no more than a page-and-a-half in length; usually less, usually focused on plot. It's often a concise distillation of a story that exists in longer form, such as the synopsis of a script found in a coverage. (Wordplay)
Beat Outline: A beat outline is a sparsely-written list of scenes or events. Useful for production draft work, it's a quick way to visualize chunks of story, follow story logic, make changes, etc. (Wordplay)
Log-Line: A log-line is a bit more full than a premise. Written in one or two lines, you get the central situation, almost always a main character, a sense of tone, and an idea of where the story leads. The log-line is the sort of thing you'd put in a query letter; enough to intrigue, with the promise of more, and a sense of completeness. (Beware; a premise passed off as a log line is really just a bad log line.) (Wordplay)
Premise: A premise is an idea for a story; the set-up or situation, with little or no story implied. Rarely written down to be presented. (Wordplay)

Case Studies

Royal Tenenbaums (2001)