Final Draft - Use your creative energy to focus on the content; let Final Draft take care of the style.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
Celtx - Celtx is a scriptwriting software platform with applications in a wide range of mediums but that specializes in helping screenwriters.
Manuskript - Open-source tool for writers.
Fade In - Fade In Professional Screenwriting Software is a complete application for writing motion picture...
Dabble Writer - Writing software for novelists.