PHPMaster.com has a new tutorial that wants to help you access one of the most popular file sharing sites out there, Dropbox, through your code (via the DropBox API).
In this article we’ll explore the Dropbox API by building a simple client for accessing files in a Dropbox account. The client will perform some basic operations, such as authentication, listing files, and uploading and downloading files.
You can grab the full code on github that provides you with some of the base you'll need to access the service (and help to make the tutorial a little shorter). They walk you through the process to create a new application on the DropBox Developer site and how to use the keys they give you to connect your app. The client included with the github download then lets you call things like "getFile", "putFile" and "accountInfo" to push/pull information from their RESTful API.