Want to avoid accidents and incidents on your journey home? Free site TrafficHawk offers useful information if you're a Sydney driver.
TrafficHawk draws information from RTA cameras and information feeds to provide an updated list of potential traffic problems around the Sydney area, neatly plotted via Google Maps. You can also click on traffic cameras to check a recent live view. That's probably more detail than you can sensibly process once you're in the car, but it could be very handy to check just before you hit the road.
For a more comprehensive (but not free) traffic service for your GPS, check out previously mentioned Suna. If you've got another favourite Australian source of traffic info online, share it in the comments. Thanks Marcus!