When visiting a home with a locked door, it would be great to be able to knock (or ring a doorbell) to summon the resident. The time of day you knock on someone's door could cause different reactions. For example, if you knock at midnight they may come to the door angry, or even concerned, depending on their disposition towards you. Of course, if they were out of the house, you would get a message "Nobody is home." Then you would have the option to "Break In" or "Leave". I also think it would be funny to hear their dog start barking when you're at the door!
Edit: Also, I'd like to see hours of operation posted at all businesses.