Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Tyke - Mac menu bar app that @torrez really needed to take notes
SnipNotes - SnipNotes is your clever notebook for iPhone, iPad, Mac and Apple Watch.
Thought Train - Stop using sticky notes to remember what you're doing 📒 🚫
Trilium Notes - Trilium Notes is a hierarchical note taking application.