The Dashboard listing screen can be found on the View Dashboards screen (Socialise/Dashboards). Workbook Dashboards have a small visual indicator beside their name to identify them, while Workbench Dashboards do not.
How to find a specific dashboard
The Dashboard listing screen allows you to search for a dashboard by name using the search bar, and filter the list of dashboards by the following criteria:
Access: The nature of your access to the dashboard (Owner/Shared/Published)
Sites: The sites associated with the dashboards
Owner: The owner of the dashboard