BitNinja constantly monitors the number of simultaneous incoming and outgoing connections and blocks DoS (Denial of Service) attacks.

GoAccess is an open source real-time web log analyzer and interactive viewer that runs in a terminal in *nix systems or through your browser.

glogg is a multi-platform GUI application to browse and search through long or complex log files.

AWStats is an open source Web analytics reporting tool, suitable for analyzing data from Internet services such as web, streaming media, mail, and FTP servers…

NetCrunch is a Windows Server–based network monitoring tool that boasts high performance and impressive scalability even in a single-server deployment.

Fluentd is a cross platform open source data collection software.

Nagios Log Server is centralized log management, monitoring & analysis software. Quickly & easily manage, monitor and analyze log data.

Scalyr is a server log monitoring tool.