GitX is a chrome extension that allows you to add notes/comments, only visible to project collaborators. This helps maintainers of the project to communicate with each other in GitHub itself and not use any other communication channel. Context matters!
Hacker Memo is a simple memo app that pursues "coolness". The design is based on the image of science fiction and spy movies such as "The Matrix" and "007".
Notes SE is a light-weight notepad app that works on your Mac, iPhone, iPad and Apple Watch. It has clean and simple interface which let you write down with ease. The data syncs through all your devices fluently using iCloud sync without separate account.
When practicing writing habits such as memos, journaling or anything you write, sometimes you want to have it sent back to you the future so you can know what you were thinking in the past, or even to audit if your projections to the future is right.
Edit Pad is an easy and clean Online text editor and note-taking tool. Take notes online and download them in a text format. Great for taking quick notes in between meetings.
GitNoter is an open source web application that allows users to store notes to their github repository. It supports markdown format, so you can add links, tables, code sections to your notes.