The Australian annual WIA National Field Day takes place on the weekend of the 13th -14th April 2013.
This coincides this year with the IARU World Amateur Radio Day weekends (the IARU day falls on the 18th and it is suggested to celebrate this event the weekend before or after this date).
Details of the IARU W.A.R.D. - http://www.iaru.org/world-amateur-radio-day.html
Details of the WIA National Field Day - http://www.wia.org.au/members/contests/nfd/
Registrations are just starting to come in for the WIA NFD, whose aim is NOT a contest, rather a publicity event to introduce the hobby of Amateur Radio to the general public, to attract more people into the hobby.
The Central Coast Amateur Radio Club, on the Central Coast of New South Wales Australia, is leading the way with two stations (VK2WFD/Pand VK2EH/P) registered to be active on Sunday the 14th.
CCARC - http://www.ccarc.org.au