Directory full of Markdown files, synced across machines/devices via Dropbox. On supported platforms (iOS/Android/OSX), I use iA Writer to edit them. On Linux,

Directory full of Markdown files, synced across machines/devices via Dropbox. On supported platforms (iOS/Android/OSX), I use iA Writer to edit them. On Linux, I use vim/goyo and Typora. I find that this is the most flexible and multi-device option, which then makes it easy to copy-paste content into other tools and places (email, GitHub, GDoc, whatever). For very quick mobile notes, I also use Pushbullet to send myself a kind of "reminder" to pick up a thought from my phone and continue the thought when I get to my laptop/desktop. I also have Simplenote installed everywhere (including simplenote.vim and native apps across Android / iOS / OSX / Linux) which I tend to use to quickly jot down notes during meetings, but for little else besides that.