Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
PodBooker - The easiest way to get booked on podcasts
pretix - pretix helps you to sell tickets for your event in an easy way. It supports multi-lingual events and provides a wide range of features
PodKoi - Find podcasts to be interviewed on & guests to interview.
Ticket Tribe - Sell tickets online with no fees per ticket
Speaker Directory by HeySummit - Guests for your next event or podcast (or submit yourself!)