The Chamber of Opportunity was where the Grand Nagus of the Ferengi Alliance oversaw all financial prospects from his throne. It was located in the Tower of Commerce on Ferenginar.
In 2374, Ishka commented that one day a female would climb the 42 flights of stairs to the Chamber of Opportunity and take her rightful place as Grand Nagus. (DS9: "Profit and Lace")
In "Ferengi Love Songs", the Nagus is seen holding court in a room not named in the episode, but called the Chamber of Petitioners in the script.