Ticket Master is the big gorilla.
Long Tail players
Ticket Web - whoops Ticket Web is a self-service online ticketing and event marketing application operated by Ticket Master, the world's leading ticketing company. The proprietary system allows venues and event providers of any size to manage the full range of box office operations on the Web, with the added value of integration and distribution through Ticketmaster.com, the world's #1 ticketing portal. Ticket Web was established in 1995 and currently serves more than 3,000 venues, events and promoters across the United States, Canada and the United Kingdom.