Mindful
Mindful combines an event reminder and a mini calendar in a system tray application. Define your own events and/or select from the list of 72 predefined common events including many US, Canadian and Jewish holidays. Use it to be reminded of appointments, anniversaries and any occasions, recurring or not, that you never want to miss again. The date of an event can be specific like an anniversary, which occurs on the same date every year, or it can be formulated, like a meeting that occurs every 3 months...
Mozilla Lightning Project
Mozilla Lightning Project is a redesign of the Calendar component. Its goal is to tightly integrate calendar functionality (scheduling, tasks, etc.) into Mozilla Thunderbird.
Calendar Magic
Calendar Magic is an easy-to-use program that is entertaining, informative, educational, and of equal applicability in the home and in the office.
UKs Kalender
UK's Kalender is a program intended to remind you of upcoming events and to-dos. There are several views for your dates that are organized similar to a calendar sheet. Dates and appointments can be entered into the calendar via an input form. You can enter a forewarn time, so as long as "UK's Kalender" is running in the background you'll be reminded of your dates as soon as the forewarn time is reached.
VueMinder Calendar
VueMinder Calendar is the future of appointment management. With other calendar apps, you'd enter the date and time of an appointment, and that would be it - maybe you'd get a simple popup reminder, but that's the best that you could expect. With VueMinder Calendar, you'll be on the receiving end of content-rich popup reminders, desktop alerts, and reminders that can be sent to you via email or direct to your phone using SMS.