A Self-hosted .ics feed aggregator that publishes an anonymized public schedule to a GitHub repository. A light weight, ultra simplified, copyleft alternative to cal.com. Looks like it outputs Markdown, which would be ideal for a repo at Github. Anonymizes event details (can you turn this off?) Publishes formatted schedule to public repo (can we change this to private?) Automatic syncing via cron.

CalView is a React-based calendar that integrates with a Radicale CalDAV server. It allows users to view, create, edit, and delete events, all synchronized with a Radicale backend. Has all of the features you'd expect of an online calendar.

A Huginn agent that can read Google Calendars using the GCal API and emit events based upon what it finds.

Wavelog is a self-hosted PHP application that allows you to log your amateur radio contacts anywhere. All you need is a web browser and active internet connection. Wavelog itself is an enhanced fork of Cloudlog by 2M0SQL.

The Debian project's canonical list of groupware available for Debian.

A portal site at which people share calendars of various sorts which you can watch using Outlook, Thunderbird, Sunbird, or Google Calendar. In Apple iCal format (which is fast becoming a standard).