Hey Dan,
You can set up a trigger campaign for those you send the email. The trigger would be "Visits Webpage" and the filter would be "Was Sent Email." Their munchkin code will be able to track their behavior and if they visit a webpage, or one in particular, you can send an alert, add them to a list, create a follow up task, etc.
If this strategy is something that you will continue to use, I would recommend creating a channel for it where visiting a webpage is the success.
Just one approach!