Crontab UI - Easy and safe way to manage your crontab file
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Scheduled tasks - GNOME GUI for configuring a users' cron (automatic jobs). Some of its features are:
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
024h Lucky Reminder - 024h Lucky Reminder is a reminder software for home and office.
Ticket Tribe - Sell tickets online with no fees per ticket