We send an alert email to the lead owner when a lead fills out more than x number of forms (e.g. resource downloads) in a given timeframe or visits a key webpage.
You could add a boolean field to the lead record that a smart campaign scheduled to run each week would set to true if the lead filled out x number of forms and/or visited x number of key web pages, etc. during the prior week. If the field is synched to Salesforce, you can create a report that is keyed on this.