HLmaps is a pair of Perl/CGI scripts for Half-Life game servers running on Linux, FreeBSD, and WinNT. It allows Web site visitors to view all your loaded maps, screen shots, download links, and some file statistics in a nice, sortable table. It optionally uses MySQL as the interim data store.
Spumoni provides an open framework for monitoring applications using SNMP. Specifically, it enables any program that can be queried via local commands to be health-checked by OpenNMS, Tivoli, OpenView, MRTG, RRDTool, and many others. This allows admins to employ enterprise-level monitoring capabilities for even non-SNMP-enabled applications.
Outstanding, esp. if you use Hibernate
Spring has a stiff learning curve for many developers, but it's worth it, especially if you use Hibernate and need to better manage transactions. Add on top of that all the other services Spring makes available (like remoting, AOP, JMS, mail, security (Acegi), singleton control, MVC and much more) and you have a stellar platform for enterprise-level applications.
Great program - especially when integrated with Ant
Checkstyle is a must-have for anyone developing Java software wanting consistency in their code and JavaDoc. It is especially useful when implemented as an Ant task - check it out!