[Zope] existing groupware products on zope

i couldn't find any existing groupware products which run over ziope... similar to egroupware or opengroupware.org. something that has the usual items such as "files, links, projects, calanders, mailing lists, ..." zope is ideal to build such user-centric groupware and project managemebt applications and i must be missing where they are. i want to avoid using apache/mysql/postgresql when Zope already is running with capacity to spare. tariq