Les Harris

The Pressbox plugin adds a new tab to the Media Upload screen that allows you to insert images and files from Dropbox into your posts.
Additionally, the plugin provides a new shortcode that lets you add links or display images anywhere you want on your blog.
This plugin is under heavy development so please feel free to send me feedback, bug reports, and feature requests!
Credits:
This plugin bears a great debt to the work of Joe Doleson’s Wp To Twitter plugin for his excellent example of OAuth integration with WordPress.

Pressbox

Integrates DropBox with your blog allowing you to post images and files directly from your DropBox. Requires PHP 5.2 and cURL.

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.

Pressbox vs Post via Dropbox