Coffee -- I actually like the smell of dark coffee being brewed more than the taste of it.
Roasted root vegetables
Black pepper
Herbs in vinaigrette -- particularly tarragon or dill, and arugula
Tomato sauce cooked slowly
Meringue -- just as it browns. Similar to a marshmallow roasting

A smell that I have grown to dislike over time is eggs of any sort. Used to like them, now I have trouble eating them regardless of preparation