Swiftdrop

Swiftdrop is a simple and non-intrusive Mac OS X dock-based utility that will help you quickly share files or folders via drag and drop using your Dropbox account.
Whenever you drop a file or folder on its dock icon, Swiftdrop will automatically copy it to your Dropbox Public folder.

When the file/folder's upload is complete, its public URL will be automatically copied to your Mac's clipboard, for easy sharing.