Visio has a nice feature, which allows you to link data to shapes. This allows you to create interactive dashboards for example, display data graphics which reflect the current state of some system on Visio diagrams, etc.
One thing may is occasionally needed, is a possibility to update your data source from Visio diagram. Meet the new add-in: BackSync
This add-in uses Visio data-binding infrastructure, and allows you to update the data in the external source from Visio (back-synchronize). There are limitations of course, but basically it should work with most data sources which support update (including Excel files, databases, and SharePoint lists).