The Darwin Calendar Server is a standards-compliant server that allows multiple users to collaboratively share calendaring information. It provides a shared location on the network to store schedules, and allows users to send each other and manage invitations. In order to provide interoperability with multiple calendaring clients, the server implements the CalDAV protocol, which is an extension of WebDAV, which is in turn an extension of HTTP.
Stratagus is a cross-platform real-time strategy gaming engine. It includes support for playing over the Internet/LAN or playing a computer opponent. The engine is configurable and can be used to create games with a wide range of features specific to your needs. Some games based upon it include Battle of Survival, Wargus, and Battle for Mandicor.