Flusurvey measures influenza trends in the UK. It effectively does this by asking people to register with them on their website and then report any symptoms of flu back to them on a weekly basis during the flu season. The more people that sign up to the survey the greater the understanding and tracking of trends can be obtained during the influenza season.
The Flusurvey website has further details on the project and also archived results in the form of interesting diagrams. The survey is open to residents in the UK. Simply register with flu survey and report back once a week.