Twitter is a service for friends, family, and co-workers to communicate and stay connected through the exchange of quick, frequent answers to one simple question: What are you doing?
PHP Twitter is a (wrapper)class to communicate with Twitter.
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/twitter_oauth/docs.