Found this the other day, as I was looking for an easy way to share files and images like how Dropbox worked.
This however, requires that you have your own hosting with SFTP/SSH permission. If you have that it works pretty much like Dropbox. You place your files in a local folder and it Syncs the files with your FTP/hosting. Very easy to set up and use. It can also generate a public link for easy sharing just like Dropbox.
It's free/open source, and Storage/Bandwidth is only limited to how much your host/ftp server provides you with.
check it out. I like it a lot.