About a year or so ago I tried to write a flash fic using an aroma-based magic system. I called it "Aromagic." The story kind of flopped after 163 words, so I put the fragment in a folder I called "Seeds" and let it sit there. I don't intend to use this story as it is, so I'll post the first paragraph here so that you can get a glimpse of how the magic is supposed to work.
Magenta edged along the cavern wall, crouching as far as she could without crawling. At the next branching of the tunnel, she pulled a small stone from the pouch at her hip. The reaction lasted only a few seconds. It changed the stone from gray to pale blue, then broke it in half. The air held only mild aromagic here, yet a good sniff would have sent anyone without Magenta’s gift to the hospital.
The idea here essentially is that aromagic exists in certain places naturally. This form of magic can kill those who aren't gifted with the ability to withstand it. Special stones can be used to detect aromagic and to negate its powers. The aromagic can be used for such actions as creating undead soldiers and encouraging plants to grow.
I could always use the concept of "aroma magic" in a different way than I have described here, but I think this tiny set of parameters that I have set should work well with the system. Hopefully some day I will finish a story using aromagic.