I really like Govinda's Hare Krishna restaurant in Northbridge. It's pure vegetarian, and while it's not flashy, it offers yummy affordable traditional Indian food including rice, dahl, vegetable curries, pappadams and their yummy semolina sweet, halava. If it's finger food you're after, they also sell samosas and pakoras.
Annalakshmi on the Swan - a vegetarian restaurant who's website mission states that "Annalakshmi welcomes guests from all walks of life where one pays what his/her heart feels" - you pay as much as you feel you want or need too. An amazing, unique dining experience! The restaurant is on the Barrack Street jetty.