I’ve always had a special fondness for date math and trivia and supporting date and time data. I’ve implemented custom solutions for clients on various groupware packages. The Open Source Development Lab recently did some research on finding an optimal server that would run on Linux and support calendaring and meeting processing across several client platforms. A perfect solution was not found (when is one?), but they chose to publish their results to help others in their search, posted here: Cross Compatible Calendaring