Graylog2‘s moto should be LMFAO (logging my freaking apps off).
Graylog2 is lovely little Splunk-like server that collects your logs and provides a nice interface for searching and analyzing them.
From the site
Graylog2 is an open source log management solution that stores your logs in ElasticSearch. It consists of a server written in Java that accepts your syslog messages via TCP, UDP or AMQP and stores it in the database. The second part is a web interface that allows you to manage the log messages from your web browser.
They have lovely screen shots here.
The only problem with it is it has quite a few moving parts that need to be installed that are not traditionally easy to get going on CentOS.
So, here is my guide.