Lightning App Builder is a point-and-click tool that makes it easy to create custom pages for Salesforce1 and Lightning Experience.

Fantastical is the calendar app for Mac.

Kopano is an open-source groupware application suite originally based on Zarafa.

OwnDrive is easy to use free online storage service for businesses, professionals, and individuals to store, backup, collaborate and share files with others.

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

Memotoo sync all your contacts from Gmail, Facebook, phone, Thunderbird, Outlook, etc in a single address book.