Bacon cooking. Mmmmmm... At uni I had a muslim friend who wasn't supposed to eat pork (she wasn't actually that much of a practicing muslim, it was more just habit from living with her parents) who we turned into a heathen because she couldn't resist the smell of cooking bacon.
I also live about 100m from the McVities biscuit factory in Manchester, where most of the world's Jaffa Cakes are made, and if the wind's in the right direction everything smells of chocolate buscuits.