Reminduck - A simple reminder app made for elementaryOS with Vala and GTK. - matfantinel/reminduck
Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
Reminder Commander - Reminder manager that reminds you about important events in advance.
Gnome Clocks - Clock application designed for GNOME 3
incron - This program is an "inotify cron" system. It consists of a daemon and a table manipulator.
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.