When we were selling our house in Texas our Skybell was great for seeing how many people were coming and looking at the house and how long they were staying. A few times we were able to overhear their conversation about what they liked/disliked about the house.
It was also great for knowing exactly what time our son got home on the weekends, when packages were delivered and whether or not I wanted to answer the door by seeing if it was a sales guy.