ostlund

This plugin lets you insert a upload form on your pages so visitors can upload files to a Dropbox account.

Dropbox Upload Form

Inserts a upload form for visitors to upload files to a Dropbox account

PaoloBe

Post via Dropbox is a easy way to update your blog using Dropbox, the famous cloud sharing service. It permits to add or edit your posts with text files uploaded via Dropbox.
Once you linked your Dropbox Account, you can upload text files into your Dropbox folder for updating your blog. It supports also Markdown syntax. 
Everything happens automatically and without further actions on your part.
Please read the readme file or Help & Faq section for further informations and instructions.
Post via Dropbox requires WordPress 3.0 (and above), PHP 5.3.0 (and above) and a Dropbox account.

Post via Dropbox

Post via Dropbox allows you to post or edit your blog with text files uploaded via Dropbox. It just works seamlessly without any effort.

Dropbox Upload Form vs Post via Dropbox