Comment by systemtrigger

There are marketplaces for speakers: espeakers.com, orate.me, bigspeak.com, kepplerspeakers.com, speakermatch.com, eaglestalent.com, celebrityspeakersbureau.com, among others. The speaker profiles include prices, areas of expertise, and a way to inquire and book. What they don't show, that you're asking for, is speaker availability and popularity. The problems I see with disclosing the schedules of speakers: 1) celebrities have real privacy concerns, 2) talent does not want their real demand every day of the year exposed to the public because it can hurt the mystery of their appeal, and 3) disparate calendaring methods maintained by each speaker mean that no web site can be in sync with all of its talent thus instant online booking is hard to do. As for the popularity requirement you asked for ("well-regarded") this is difficult to define because assessments are nonstandard; so what you get in all speaker marketplaces is endorsements and accolades the speaker cites themselves in their own profile -- which will always be self-recommending.