Scrivener: a word processor and project management tool that stays with you from that first, unformed idea all the way through to the final draft. Outline and structure your ideas, take notes, view research alongside your writing and compose the constituent pieces of your text in isolation or in context. Scrivener won't tell you how to write—it just makes all the tools you have scattered around your desk available in one application.
I credit this tool with helping me hammer through my first draft!
Scrivener also has a ton of training vids on YouTube:
--It's a GREAT tool and only $40!