ownCloud is a free and opensource file sync and share app which is self hosted.

Fantastical is the calendar app for Mac.

Wimi is a collaborative platform, for file sharing and online project management.

AkrutoSync helps you automatically sync Outlook across all devices.

Glip is fully searchable, real-time group chat; video chat, task management, file sharing app.

Baïkal is a Cal and CardDAV server, based on sabre/dav, that includes an administrative interface for easy management.

fruux is a cross-platform synchronization service.