Assuming you want to do Black and White printing, I can think of 3 off-hand. Others may know of some more.

1) Pointlight in Surry Hills
http://www.pointlightworkshops.com.au/DROOM%20HIRE.htm

2) Blanco Negro
http://www.blanconegro.com.au/

3) Australian Centre of Photography
http://www.acpworkshop.com/index.php...ility#darkroom

I use number 3 as it is slightly cheaper than the others, particularly if you buy blocks of time. The facilities are fairly standard. LPL 7700 B&W enlargers. Kodak chemicals are used and are set up by the staff. I haven't tried the other 2 but they appear to be quite reputable.

Best regards,
Thanasis