David Winer has announced Fargo, a new version of the Little Outliner that saves to Dropbox. Make sure you want it to hook up to Dropbox before you click on this link.
Winer has big plans for this application: "This is the beginning of a journey. We plan to hook Fargo into everything. And because it uses an open document format, OPML, other developers can hook into the idea flow of Fargo users. The possibilities are endless."