A resource reference is detected in a base resource, such as a web page or an email message. The resource reference refers to a target resource, such as another webpage or another email message. An appropriate activity-based resource type for the resource reference is then identified. The resource reference is then linked to an activity-based resource such that when the base resource is displayed and a user interacts with the resource reference, the activity-based resource is displayed to the user. The activity-based resource comprises a calculated field that has a value that indicates how one or more users have interacted with one or more resources. The value of the calculated field is calculated using activity data indicating how users interacted with the resources. The activity data is generated without receiving input of the activity data from the users.