Travel comparison site Kayak, which compares pricing for hotels, flights, cars and holidays from different sites, has long been a Lifehacker favourite. The addition of Australian dollar pricing makes it even more useful.
Search for a hotel on Kayak and you'll see the pricing from multiple providers, including Expedia, Hoteclub and Hotels.com. Similarly, search for a flight and you'll see options from most major airlines. Booking is still direct through those sites, so it's easy to find the best possible price for any given venue.
You can filter for price or ratings, or ask to see only 'good deals'. Definitely a useful resource for travel planning.