I was asked why I carry a Sonic Screwdriver.
Aside from the thousands of obvious uses for a sonic screwdriver, the best one, is that it is a great conversation starter. Now, sometimes it doesn't always work, but then not everyone can understand a 907 year old TimeLord's technological equivalent of a swiss army knife.
Take those instances where you need something to set yourself apart from the crowd. For example, there is a guy who attends technical (IT) events and takes his accordian. He is known as Accordian-Guy. Everyone knows him and it's a great ice-breaker.
Take Rick Claus - a Microsoft Professional Adviser - at the Microsoft events he always wears a green hat. Its his thing, but anyone can easily recognize him and pick him out in a crowd.
Now I know Im not being terribly original with the Sonic Screwdriver, but hey. It has lights and sounds and my daughters think it actually fixes things, locks doors and makes 'owies' better.
Now I need to convince my wife to let me build a shed in the garden that looks like a 1963 police box