After visiting Ballarat Aviation Museum, we went to Ballarat Wildlife Park. This zoo is famous by its animal shows or meet the keepers, when you will have a chance to pat koala and wombat.
You can also see free roaming kangaroos, Tasmanian devils, eagles, giant tortoises, crocodiles and alligators, lizards and both venomous and non-venomous snakes. With the kangaroos, you can hand feed them (you have to buy food with the tickets). We were lucky, as a lady, who was exiting the zoo, gave us an almost full pocket of kangaroo's food. But kangaroos didn't want to eat it! May be they were full, probably, it was too hot for them on that particular day - I still do not know.
To sum up, the park is a good place to visit if you'd like to pat koalas, otherwise, I would recommend you to visit Healsville Sanctuary - there is much more Australian animals there, rather than here, in Ballarat.