Final Draft - Use your creative energy to focus on the content; let Final Draft take care of the style.
Manuskript - Open-source tool for writers.
Celtx - Celtx is a scriptwriting software platform with applications in a wide range of mediums but that specializes in helping screenwriters.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
StudioBinder - Production management made modern.
Storyline Creator - An elegant tool for authors to write, organize and visualize their stories.