Have you ever wondered what the Google people know about you? They know who Dr Grumble is. They may even know he was a little off colour this weekend because Dr Grumble was searching to find out what were the active ingredients in the cold cure Mrs Grumble brought home from the local shop. As well as being able to guess that Dr G was a little under the weather Google can also do some real time epidemiology. When the long-feared 'flu epidemic arrives Google may well be the first to know. Here's how.