The Macedon Chamber of Commerce was a financial institute located on the planet Macedon III.

After hearing Lieutenant Lex Nakashima talk about all of the tourist spots on Macedon, Doctor Leonard McCoy asked him if he was working for the Chamber of Commerce. (TOS - Star Trek II Short Stories short story: "Under Twin Moons")

As the Chamber of Commerce was only mentioned in jest by McCoy, it is possible that it was just an invention on his part.