pisg is an IRC channel statics generator written in Perl, it creates statistics from different logfile formats. It was originally written because IRCStats wasn't open source. So here's an open source/GPL'ed version to anyone interested.
mIRCStats is a highly configurable yet easy-to-use log analyzer for virtually any kind of logfiles. It was originally developed for analyzing IRC channel log files created with mIRC and later with any IRC client.