I run across an OpenLDAP log file analysis tool. It’s written in Perl and will walk through the log file created by OpenLDAP (logging is performed through syslog) and report on various things like (taken from the website):

operations (e.g., Connect, Bind, Unbind) performed per host, unindexed searches, attributes requested, search filters used, total operations per server, and operation breakdowns by day, hour and month.

There’s also a statistics collector (collects data from cn=Monitor) that can be used as an input for graphing application in order to create graphs of server statistics.