One of the more comprehensive and useful reports is the CSV Facesheets available in System Reports. From the navigation menu Select Reports | System Reports |  CSV dropdown | Facesheets to access the facsheet. This will download a .CSV file.

The Facesheets can be opened in excel editing and configuration to filter specific information. The data includes all of the completed fields on the "Persons and Institutions | Patients" page for each active patient.  

The configuration of your account will determine the amount of columns that appear. These columns include complete demographics information including contact details, insurance information, and other information about the client. The Facesheets can be used to filter specific information that your practice needs that way not be available via an existing report. It can also be used for things like mail merge and getting email information for all patients for mass communication to clients.