Unimaginatively-named Calendar is a Web calendar application written in Java with a MySQL database. Calendars can be made private, semi-private, or public with a password-protected admin section. Subscriptions can be created to pull events from remote iCalendar sources and, of course, Sunbird and iCal users can subscribe. The display is easy to read and prints very well; its design is controllable using (customizable) themes that can also be used to filter events. Repeating events are supported, and single events can be scheduled at multiple arbitrary times (even if they don't form a pattern).
Attendance is a Web application for taking and tracking attendance records online. It is perfect for volunteer groups, especially youth-oriented groups, where participation counts for some kind of credit. Attendance allows you to categorize the roster and hide inactive members. It allows you to create "attributes" to track additional information on each attendance record (e.g. "Late"). It creates several printable reports.
spamdyke is a drop-in filter for qmail to provide connection-time blacklisting, graylisting, DNS RBL/RHSBL checking, sender MX checking, improved logging, and more. spamdyke will provide SMTP AUTH and TLS to unpatched qmail servers. Installing spamdyke does not require patching or recompiling qmail.