Outliners, such as Omni Outliner Pro, MyMind or Deep Notes (All covered in the Software Reviews section) are great tools for organizing lists of tasks, projects, ideas etc.
By shuffling items up and down within the list, or nesting them within other items, we can play around with our information; hiding what's distracting—emphasizing what's important.
Now there's Loose Stitch—an online outliner that works in Firefox, Safari and iPhone. It works in much the same way as any stand-alone outliner, and can even import your existing files provided they are in the universal OPML format.
Why work online? Because now you can invite others to collaborate on your outlines, work on them when you're out and about, and even embed them in regular web pages.