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

Denis Buka

This plugin allows you to upload single files or entire directories with subdirectories to your Dropbox account. You can use it for backup, synchronization or whatever uploading tasks you may have.
Features overview:
<ul>
<li>Upload entire directories with subdirectories to your Dropbox account. </li>
<li>Backup your entire site files by pointing to the WordPress installation directory. </li>
<li>Specify a Dropbox folder to which your files should be uploaded. If such folder doesn’t exist it will be created. </li>
</ul>
My other plugins:
<ul>
<li>Intuitive Navigation (https://wordpress.org/extend/plugins/intuitive-navigation/) </li>
<li>Generate Cache (https://wordpress.org/extend/plugins/generate-cache/) </li>
</ul>
Links: <a href="http://steamingkettle.net" rel="nofollow ugc">Steaming Kettle Website Design & Video Production Studio</a>

Drop in Dropbox

Upload single files or entire directories with subdirectories to your Dropbox account.

Dropbox Upload Form vs Drop in Dropbox