Try sailinganarchy.com/ The forums include Crew Pool Anarchy. The description on the website says it all: "Come here to find a body. Or donate yours. Post your requests and a way to contact you. ..." Good luck!

The CYC maintains a register.
see here for info : http://www.cyca.com.au/editorial.asp?key=4788

here is an extract......
"If you are an experienced sailor who is interested in being placed on the Register of Interested Crew, please send an email, detailing your offshore sailing experiences, qualifications, preferred positions on the boat, contact information and crewing goals to [email protected]"

the other 2 main ocean racing clubs are Middle harbour yacht club (MHYC) & the Royal Sydney Yacht Squadron (RSYS) not sure what arrangements thay have.

good luck.