Feng Office is an online project management and collaboration software. It allows to manage tasks, events and meetings, time tracking; group communication, document editing and sharing, gantt charts, billing for customers and vendors. It's available as open source community version or SaaS.
The Zarafa Collaboration Platform is a Microsoft Exchange replacement. Zarafa provides an integration with an existing Linux mail server, native mobile phone support by ActiveSync compatibility and a WebApp with 'Look & Feel' similar to Outlook using Ajax. Including an IMAP and a POP3 gateway as well as an iCal/CalDAV gateway, Zarafa can combine the usability with the stability and the flexibility of a Linux server.