We are building a Saas all called Flow. It's a sales productivity tool for salespeople.
We tell you what happens to your documents/presentations after you hit send.
Flow is a web app that shows salespeople how their leads interacted with a presentation they emailed them: if they looked at the presentation, what slides they looked at, how long they looked at each slide, and who they forwarded it to.
It helps sales people find out what leads are hot based on their engagement.