Rainlendar - Rainlendar - Customizable desktop calendar
Reminder Commander - Reminder manager that reminds you about important events in advance.
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Date Reminder - Date Reminder reminds you of recurring or nonrecurring events, like birthdays, bills to pay...
Scheduled tasks - GNOME GUI for configuring a users' cron (automatic jobs). Some of its features are:
JIT Scheduler - JIT Scheduler is a task scheduler for Windows 95/98/ME/NT4/2000/XP/2003.