Rebel Notes - Rebel aims to provide you a distraction-free note taking experience. Focus more on writing and less on formatting and saving. As you write your note, Rebel will format it based on your markdown syntax.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
Notepin - Extremely simple note-taking + blogging ✍️
EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.