When I saw going to the US earlier this year, it was really difficult to find an Aussie-to-US adaptor, except in some travel shops where they were ridiculously expensive. I managed to find this universal adaptor in Malaysia for RM17, less than a quarter of the price of an ordinary adaptor. I found it in an ordinary hardware store. Later that day, I found a large selection of universal adaptors in a departmental store in One Utama, but I still like this one best. Now, wouldn't it be perfect if it has a USB charger built in as well?
(The images show the two sides of the adaptor. One side shows all the pins fully extended. For Australia and US use, the pins can be turned at an angle)