The Australian Taxation Office estimates $17 billion of superannuation is lost, and has a service called SuperSeeker to help members track it down. It's worth taking 10 minutes to check for yourself or anyone in your family, perhaps from a long-forgotten part time job. Go to ato.gov.au.
You can use SuperSeeker to check super accounts that have received money for you in the last two years, find your lost super or even transfer your super to another fund.