Little Outliner is a new editor from Dave Winer that automatically saves text locally. The HTML5 web app is a simple, straightforward way to create outlines.
Here's a quick how-to for using Little Outliner. You can expand and collapse headlines hierarchically and move things around with your mouse.
For example, you press return to make a new bullet point, or hit tab to move one over. Basically, if you've ever used a text editor, Little Outliner will make sense to you. [Little Outliner -- h/t @tcarmody]