Erik recently came across a website called ModernPostcard.com. They give you a small piece of code that you can drop onto your website to track what users come to your website. That code results in the company looking up the IP address of the person that came to your website then finding the physical address from there. With the physical address, you can have a postcard automatically sent to them.
This postcard is customizable and can be the introduction to the sales funnel.