Tools

These tools can be used for system log file analysis:

• Logwatch - log file analysis system
• Yet another advanced log analyzer
• Prelude - Hybrid Intrusion Detection System
• OpenWebStats - PHP Web Stats for Everyone
• SourceForge.net: Project Info - Sentry Tools
• ModLogAn - Log File Analyzer
• polliwog - Java Web-log Processor

These tools are mainly oriented towards web log file analysis:

• Yet another advanced log analyzer
• OpenWebStats - PHP Web Stats for Everyone
• ModLogAn - Log File Analyzer
• polliwog - Java Web-log Processor

These tools monitor daemons or servers

• Prelude - Hybrid Intrusion Detection System
• monit - UNIX system management
• watchdog - System monitor
• mon - Service Monitoring Daemon

For the system log analysis I stick to logwatch, for the service monitoring I am running monit.