Gurts has the best frozen yogurt in the city. They seem to switch the types available on a regular basis which is kind of cool because you can always try something different. They have both fresh fruit and sweet toppings (chocolate, m&m's, coconut flakes etc). Way better quality than Menchies!
They also have awesome baked goods - tarts, cupcakes, cookies etc. I have gone in there a couple times to buy an assortment for dinner parties. They always go over very well!
If you live in Roncesvalles, this is a great local spot - the guys that own it are really nice too.