If you have ever visited StackOverflow.com you may have noticed the ads for Splunk.  Splunk aggregates log files together and provides a web interface to search through those logs.  The setup for php is easy: set the php.ini error_log value to "syslog".  The Splunk instructions show you how add a single line to your syslong.conf to have syslog send those messages over to Splunk.