Darling Harbour is currently host to a number of great vessels, including some naval ships and submarines, as well as HMB Endeavour - a replica of James Cook's tall ship [next to lighthouse]. If you have some spare cash you can sign up for a leg of Endeavour's first circum-navigation of Australia, in 2011.
One of the museum highlights is an exhibition - On Their Own - about Britain's child migrants to Australia. From the 1860s onwards over 100,000 British children were sent to Commonwealth countries through child migration schemes, supported by the governments and organised by charitable and religious organisations. Most of the children were told that they were orphans and had no choice but to leave. Now adults, many migrants are discovering living parents and relatives in the UK and trying to come to terms with their past. The photographs, diary accounts and interviews with the child migrants decades on, reveal that although many children were removed from a life of economic hardship, they embarked on a new life of suffering and sorrow, which a suitcase of new clothes didn't compensate for. These children helped form the backbone of the Australian economy. This was an exceptionally moving encounter with British and Australian history and I wasn't the only visitor with tears in my eyes.