Is there an offline maps application for Android? Google Maps is great, but unless you have an unlimited data plan, it's going to cost a lot downloading all that data all the time.

Do you know of any (preferably free) good offline map application for Android? Ideally one that can do navigation (preferably with voice) and in my location (Sydney, Australia).
Yah, there is a terrific one, called Maverick Lite.

Off-road GPS navigator with OSM, Google and Bing maps. Support for offline maps &amp; multi-touch. Build-in compass, timer and trip computer. Share your current or planned location. Record and upload tracks to GPSies.com. FourSquare support.

And it's free. the paid version costs about $4