Hey Jacqui, I live in Sydney too and definitely have a few favs! Naked Basil on King Street in Newtown is great. This place serves Vegan breakfast, lunch and dinner! Dinner is awesome vegan pizza which I always follow with a vegan dessert such as heavenly vanilla slice and a to die for 100% vegan hot chocolate. The even hand great the chocolate on top!
Just across the road from Naked is Green Gourmet, a lovely Tao Asian vegan restaurant and down the road a bit is Green Palace, Vegan Thai. In the city on Erskine Street there is Peace Harmony which is also vegan Thai and has a beautiful atmosphere.
Another place I just discovered is a Japanese restaurant on York Street opposite where the buses pull up in front of the QVB, closer to the Town Hall end. You need to go down some stairs to get to it. It isn't a vegetarian restaurant, it serves traditional Japanese sushi, noodles, etc, but you can get a great vegan feed there. I ordered the "vegetarian lunchbox" which consisted of misu soup, all different types of vege sushi, marinated eggplant and several other vegan japanese delicacies I didn't even know existed.
Another style that is great for vegans is lebanese. There are a few lebanese restaurants up Surry Hills way on Cleveland with plenty of vegan options. I think one I went to was called Nada's. My cousin and I had a very tasty vegan banquet there with cinnamon tea and it was pretty inexpensive too..
Oh! and have you been to Govindas yet? Govindas is always such a fun night out. They have special dinner/movie packages where fist you dine at a great vegetarian Indian food buffet, then head upstairs for a movie. Except the movie theatre isn't like boring Hoyts, they have big comfty sort of lying-down armchairs! check it out:
http://www.govindas.com.au/page/how_rest_cinema_works.html
hope this helps! Happy dining!