The Play.net Box Office site handles sales for ticketed events in Gemstone IV, generally revolving around festivals, quests, and Cathedral Weddings. This is still a live link on the Gemstone IV homepage, and when you are logged into your account, it also has options for you to view your past purchases. Note that Simucoins have increasingly been taking the place of outright Box Office ticket sales for events.
Current Box Office offerings
For events not listed, or to schedule a private run of a quest, contact firstname.lastname@example.org.