Dropbox is the easiest way to store, sync, and, share files online. There's no complicated interface to learn. Dropbox works seamlessly with your operating system and automatically makes sure your files are up-to-date. Available for Windows, Mac, and Linux.
PHP Dropbox is a (wrapper)class to communicate with Dropbox.
PHP Dropbox is BSD licensed.
The class is well documented inline. If you use a decent IDE you'll see that each method is documented with PHPDoc. More documentation can be found on http://classes.verkoyen.eu/dropbox/docs.