OneTask is designed to help you focus on a specific task or goal that really needs to be completed. It does this by letting you define a single item and place it prominently on your menu bar for a visible reminder to get whatever it is done.
Plume is a simple note-taking app that lets you write down your thoughts. It also has an inbuilt to-do list button that lets you quickly generate to-do lists.
PopDo is a task list app that sits in your menu bar. It integrates with Apple Reminders and with iCloud.
Quick Note is a clutter-free note-taking in your menu bar. optimized for a fast and quick note-taking experience. The Note floats on top of all other apps, so your notes are always visible.