Calendar Lock PEA - Calendar Lock PEA is an encrypted desktop calendar with a day, week and month view. The shown calendars are never stored unencrypted on your disk, but exist only in the RAM. Platform-independent, Open Source, no installation or registration required.

Reminduck - A simple reminder app made for elementaryOS with Vala and GTK. - matfantinel/reminduck

Simple Calendar - A simple calendar with events (optional recurring and reminders), week numbers and a customizable...

Memo to Me - Online email & SMS reminder service.

UKs Kalender - This program helps you organizing your dates and tasks and reminds you of upcoming events.

Simply Remind Me - Free email and text reminder service so you don't forget the important things in life!