AirServices Australia is the body which provides Air Traffic Control at towered airports and in controlled airspace throughout Australia. They also produce all the charts and documentation used by pilots and others in the aviation industry.
The Civil Aviation Safety Authority is the organisation charged with regulating all aviation in Australia, to ensure the safety of the travelling public. Their responsibilities extend to the sport and specialist bodies as well, such as RA-Aus, GFA, ASRA etc.
NAIPS Login Page for Pre-Flight Briefing. All the information required for pre-flight planning can be accessed from these pages, including area forecasts and TAFs and METARs for specific aerodromes, and NOTAMS. There are also instructions on how to use each of the various facilities, and Flight Plans or SARtimes can be submitted here. (From 4/7/15, Username: oft and Password: ypks1267 if you don't have your own. That's Parkes CTAF. Be aware that AirServices requires a forced password change every six months.)
Recreational Aviation Australia is the organisation responsible for administering sport or recreational aviation in Australia. They control aircraft construction & registration, pilot training and certification and flying activities on behalf of CASA.