Tool for clickstream anlyzing of Apache logs?

Two of the best opensource web analytics are OWA and Piwik

OWA is supporting click-stream and the demo is here : http://demo.openwebanalytics.com/owa

Piwik is offering a clickheat plugin

demo : http://demo.piwik.org/

Worth mentionning:

http://greensweater.wordpress.com/2006/05/01/clickstream-tracking-with-apache/

https://github.com/riivo/pwum

The best tool that i have used is Splunk(http://www.splunk.com/download/) It's not cheap, but real cool and give best speed and functionality that you ever need. Also they have freeware license for aggregation 500mb of data per day. I used this licence on my production game servers(about 3m users) and haven't any problem with this limit