where in cambridge? i really like the vegan pizza at scallywaggles in allston,though if i am in that area i would rather go to grasshopper.
Veggie Planet, in Harvard Square. It's not all vegan, but the vegan pizzas they have are the best. If you ever have a chance, try "Vegan Oddlot Pizza with Romesco". Very cheap, great food.
Another good place (expensive but good) is Grezzo in the North End. All vegan.