I watched a TV advert for Sat Nav or Satellite Navigation to those who are still struggling to get to grips with their in-car stereo.

Apparently you can now buy systems that guide you from A to B (from reports in the popular Press, that usually means from motorway to cliff edge) in the voice of famous people, one being Marilyn Monroe.

I rather fancy Ian Paisley or possibly Arthur Mullard using their gravelly tones to tell me how to reach the local fish and chip shop.

Either way, as a time-served Luddite, I have to admit, in my limited experience (one journey), I am impressed with Sat Nav.

And it led me to ponder whether the principle could be applied in other areas. For instance: Cat Nav: We have no idea where our beloved pet goes after dark, or what he gets up to. A hi-tech tracking device, mapping his every move, from cat-flap to next door's flower bed, to the haunts of the mangy stray moggy that flaunts herself in our garden every evening, would enable us to see whether he really is as cute and lovable as he has us believe.

Fat Nav: Much is being done to prevent obesity in children and adults. This device could be worn like a belt around the waist and, while out shopping, it would pick up on an item's bar code. It would then issue a warning as to the amount of weight about to be gained. Fat Nav would tell you, in a stern, 'sit-up-and-listen' voice: "By eating this eclair you will gain 6lbs and add half an inch to your waistline."

Rat Nav: If marketed, this little gadget would not, as you might assume, be employed by pest control officers to hunt down pesky rodents. Instead, the Rat Nav would serve as the electronic equivalent of a private detective, to track love-rats whose partners believe they are having illicit affairs. Its state-of-the-art, remote-sensor tracking device would record addresses visited and time spent there. It would even be capable of taking photographs and transmitting them to lap-tops.

Brat Nav: This high-spec invention would put an end to teenage yobs causing havoc in neighbourhoods by allowing parents to keep an electronic 'eye' on their children when they are not at home. It would inform them of their child's every move.