Australians celebrate Christmas and Easter, but for us they're just a time to get together with family and don't have the same religious significance that they do in other countries. New Year's is like that too, but since it's so close to Christmas many people just consider them one holiday. Many people spend time with one side of their family on Christmas and then spend time with the other side of their family on New Year's.
ANZAC Day is probably the next most significant event in Australia after Christmas and New Years. It's a sombre day of remembering those who have been killed in war. It's customary for Australians to attend a memorial services at dawn, but there's usually another one held later in the morning for those who couldn't make the first one.