Star Trek Door Chime: 2010 - ThinkGeek
This project is a scaled down version of the intercoms seen on the original Star Trek TV show. It's got a pair of motion sensors on the sides which trigger the 'woosh-whoosh' sliding door sound from the show or a red-alert alarm sound depending on which mode it's set to. It's also got a door-bell for people who are too wrapped up in their work or have desks which face away from the door.

Star Trek Electronic Door Chime - $29.99