Log4jRelatedResources - Logging-log4j Wiki

LogWeb servlet-based Log4j configuration facility (open source)
VigiLog log file viewer (open source)
log4jdbc SQL/JDBC logger (open source)
JAMon monitoring tool (open source) - JAMon provides a Log4j Appender that will
- Aggregate how many messages of each Level have been logged(DEBUG/WARN/...) and when each of these were last invoked
- Allow you to view a 'tail' of each Levels most recent messages via a JAMon web page
- Count how many messages of any given content that have been sent to your log (i.e. 'Invalid login by user X'),
- JAMon also provides a wealth of other realtime stats such as SQL Performance metrics, page hit times, and more.
- No code changes are required to do any of this!
- More info on the JAMonAppender
- JAMon Live Demo
Layered Configurator A configurator that uses other configurators in sequence, and can use system properties as substitution variables(open source)

WizardForge provides wizards to generate log4j configuration files: log4j.xml (1.2.x), log4j.xml (1.3) and log4j.properties.

Log4j tutorial, examples, log4j.properties vs. log4j.xml, Best practices for logging and exception handling, Tomcat configuration monitor, monitors changes to logfiles and updates the log4j configuration.