It's pretty much missing or empty data for the entire .au TLD (e.g. even google.com.au is not present).

Living here, I know that their whois server rate limits heavily and the ccTLD zonefile is not available, so I'm guessing those are probably contributing reasons. Do you guys do any crawling at all?

I think this is a fantastic concept though. Knowing that whois database and zonefile access is often protected for commercial motivations, it really irks me. Open it all up.