Buzzsaw (www.buzzsaw.com) offers a very useful way of placing files in a central server to allow distributed users to access these files if you do not have a central server and WAN for project collaboration, or if you have external people/companies working on a project and you do not want to grant them access to your local network.
Autodesk ® Buzzsaw ® software as a service (SaaS) delivers document, data, and design management solutions to architecture, engineering, and construction (AEC) firms and owner-operators. Autodesk Buzzsaw helps organizations centralize and more securely exchange project information inside and outside their organization. And with proven SaaS technology, your company can focus more on project delivery and less on managing costly IT infrastructure.
Buzzsaw comes with a Buzzsaw Sync utility which allows you to sync local folders with those on Buzzsaw. Although Buzzsaw Sync allows you to have continual syncing, you may find it more manageable to only perform syncing at certain times of the day. (This avoids continual messages to reload Xrefs.)