In the custom actions area, it allows you to expose merge fields to use as POST parameters for a VisualForce page. It would be great to be able to expose the active filter information such as data set(s) and or geographic shapes. What can be done with this information is creating custom actions that could log this information for auditing purposes in a separate object such as when you add campaign members, you would want an audit trail of the criteria used to pull that audience.