Adding new data chart components to a Dashboard follows almost the same exact steps as adding a regular component. The only difference is that you won't work with the Component Configuration wizard and you won't have the same number of options from which to choose.
You can mix and match data charts and components on your Dashboard to give you the exact information you are looking for.
As of this writing the dozen data charts that come with ACT! include the following:
Recently created contacts
Recently edited contacts
Contact history count by history type
Contacts by country
Contacts by department
Opportunities open by product
Opportunities with contact info
Opportunities by products
Opportunity weighted total by stage
Remote database information by user
Remote database sync status by user
User status
It's a good idea to be familiar with the available data charts so that you'll have a good idea of how to organize them before you head to the Dashboard...