Announce package releases, new projects, job offers, calls for papers, and events such as meetups, conferences / workshops.
Local events targeting non-English speakers may be announced in the local language (but if a special category for this language already exists, then you should rather post the announcement in this category so that it better reaches its intended audience).
Write to coq+announcements@discoursemail.com to start a new topic in this category via e-mail.