syslog-ng, as the name shows, is a syslogd replacement, but with new functionality for the new generation.
The original syslogd allows messages only to be sorted based on priority/facility pairs; syslog-ng adds the possibility to filter based on message contents using regular expressions.
The new configuration scheme is intuitive and powerful.
Forwarding logs over TCP and remembering all forwarding hops makes it ideal for firewalled environments.
