Indeed this laundry list is a great description of the services that are needed to manage documents. There's probably one more to add to the list (document generation, i.e. starting from a template like a generic NDA or an employment offer and generating a new document by inserting data like company name, expiration date, etc, into the template). Since this thread talks a lot about how to provide these features on top of Google Drive and Google Docs, you can have a look at my company AODocs (www.aodocs.com) which provides a cloud-based Documentum/Alfresco/etc alternative, using Google Drive as the underlying file storage.