[mark_l_watson]

I use several things:

leanpub: for writing books. uses Dropbox, web services to produce books from markdown. I can edit markdon files on my phone, ipad, Chromebook, and kaptops.

Google docs: quick notes that I might need in the future; having search helps find stuff later

Microsoft OneNote - for notebooks for travel planning, research, etc.

Emacs: org mode, but it takes effort to get started