Xavier Media

This plugin will do a backup of your WordPress database and, or your files in wp-content/uploads and saves 
it somewhere safe. You can have the backup saved in your <a href="http://db.tt/9Jo39Xy" rel="nofollow ugc">Dropbox account</a>, a FTP account of your choise, your 
account with <a href="http://www.securepaynet.net/email/online-file-storage.aspx?ci=1796&prog_id=xaviermedia&isc=xmbackup" rel="nofollow ugc">Online File Folder</a>, or have the backup emailed to you (not recommended for large files). You can 
select to have the backups named the same every day or to have a date added to each file name.
This plugin requires PHP, cURL, PHP compiled with ZIP support, and Oauth (for Dropbox).
** NO WARRANTY SUPPLIED! **
** Make sure you test your Backups! **

XM-Backup

Does a backup of your Wordpress database and, or your files in wp-content/uploads and saves it in a safe location.

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.

XM-Backup vs Drop in Dropbox