Remind is a sophisticated calendar and alarm program. It includes the following features:

• A sophisticated scripting language and intelligent handling of exceptions and holidays.
• Plain-text, PostScript and HTML output.
• Timed reminders and pop-up alarms.
• A friendly graphical front-end for people who don't want to learn the scripting language.
• Facilities for both the Gregorian and Hebrew calendars.
• Support for 12 different languages.

It looks pretty nice, it is able to run what ever scripts you would need to per the remind schedule file (plain text) and has PS and HTML available for viewing.

This program is becoming venerable, development since 1989, and continues to be updated.

You can check the wiki for recipes and use cases.

And yes, Virginia, there is a GUI for that. Linux Journal

Remind is a sophisticated calendar and alarm program. It includes the following features:

• A sophisticated scripting language and intelligent handling of exceptions and holidays.
• Plain-text, PostScript and HTML output.
• Timed reminders and pop-up alarms.
• A friendly graphical front-end for people who don't want to learn the scripting language.
• Facilities for both the Gregorian and Hebrew calendars.
• Support for 12 different languages.

It looks pretty nice, it is able to run what ever scripts you would need to per the remind schedule file (plain text) and has PS and HTML available for viewing.

This program is becoming venerable, development since 1989, and continues to be updated.

You can check the wiki for recipes and use cases.

And yes, Virginia, there is a GUI for that. Linux Journal