Smellitzers in-use in WDW (that I know of):
-Main Street Bakery: cookies (ice cream shop is right next door, so it may be a two-shops-with-one-smellitzer situation)
-Main Street Confectionary: smell of some type of candy, I know this changes to peppermint/candy cane in the holiday season
-Stitch's Great Escape: chili dog
-Philharmagic: apple pie
-Spaceship Earth: burning Rome
-Soarin': various smells including pine and orange
-Journey Into Imagination with Figment: skunk
-Test Track: corrosion robots
-Universe of Energy: I *believe* they have a "primordial" smell in the diorama
-Villains in Vogue shop at the Studios: candy apple smell outside the Old Hag's window
-It's Tough to Be a Bug: stinkbug
-Kali River Rapids: jasmine in the mist of the lift hill
Horizons used to have the "Loranges" smell.
Tower of Terror had one installed during its most recent changeover to the random patterns, but after the burning-wires smell freaked out some early-morning Guests when it was left on after overnight testing, it was removed.
I *think* that's it... Did I miss any?
-Rob