A list of writing tools is a displacement activity

Writing, focussing, assembling, editing, collaborating, feeding back, researching, structuring, outputting and publishing. (Updated Feb 2014.)
Focus through constraint:

• iaWriter - "Keep your hands on the keyboard and your mind in the text". Has good reviews.
• Byword - "Simple and efficient text editing". Also has good reviews.
• Writeroom - appears a generation older than iaWriter and Byword.
• Textmate - does text, html and a zillion other developer's things.

Quality:

• Hemingway - "makes your writing bold and clear".

Research speed and convenience:

• nvALT - Speeds up that did-I-already-write-about-this? moment, auto-saves, does text files, Markdown. Nice. I'm writing this post in it.
• Pinboard - elegantly executed webpage bookmarking.

Collaborating and community feedback:

• Draft - its drafts are neat version control, has premium "ask a pro", updates frequently. (Has a no-going-back Hemingway mode, thought isn't the same as the Hemingway above.)
• Poetica - "Get feedback about your writing from people you trust, wherever they are" - not released yet. Amusingly, screenshot critiques Word track changes and Google Docs. Reviewed by Rev Dan.
• Google Docs - good at collaboration and export, auto-saves. Has automated versioning but without actual version *control*.
• Editorially - "makes collaborative writing easy", via here but sadly shutting down.
• Penflip - "helps you write better with others".
• Authorea - "the collaborative platform for research. Write and manage your technical documents in one place".

Assembling, structuring, editing and eBook workflow:

• Ulysses 3 - "All your texts. In one place. Always." Not tried, but this review says "the app reimagines the text editor in a way that visually resembles Mail and conceptually sits somewhere between iA Writer and the project-based Scrivener". Which sounds like quite a thing.
• Scrivener - looks a bit of a mess to be honest. They also have Scapple, a mind map/words-on-sticks app.
• LeanPub - "Publish Early, Publish Often - Authors and publishers use Leanpub to publish amazing in-progress and completed books". Costs $0.50 plus 10%.
• Lacuna books - "the best way to write and publish a book". Big on structuring, rendering chapters and ebooks easily.
• Quip - "Beautiful documents on any device".
• Marquee - "a full-stack publishing platform...  to help everyone, from editors to designers and developers, come together to make great content for the web".

Formats and outputs:

• Marked,  because between text and html, Markdown is the popular "intermediary" format, (like nvALT) is good at simultaneous preview.
• Mou - good at simultaneous preview of Markdown, custom css etc, always seems to recover well from its frequent crashes.
• And a simple Google Apps script to convert a Google Drive Document to markdown.

Online publishing and attention:

• Medium - "A better place to read and write things that matter" - becoming a centre of gravity for serious writing, per-para commenting interesting.
• Wattpad - an ebook platform/store/agora that isn't Kindleland.

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