Jim Trails Epics, which I follow for planning my own:

2001 - ?
2002 - ?
2003 - Tharwa -> Old Bobyon Road + Fitz + Horse Gully Hut + Naas Valley (warks Road)
2004 - Two Sticks
2005 - Mt Clear
2006 - Corn Trail

Check out:

http://svana.org/sjh/rides/

26 inches used to have something about them too, but since the move, it's hard to find.

Also, great endurance races:

http://www.workingweekseries.com/
http://www.daynightthriller.co.nz/
http://www.cycleepic.com.au/
http://www.wildsidemtb.com/

And this guy does lots of bushwalking out in the Brindies and has a great website:
http://www.pcug.org.au/~jevans/