Piwik

Piwik is a downloadable, open source (GPL licensed) real time web analytics software program. It provides you with detailed reports on your website visitors: the search engines and keywords they used, the language they speak, your popular pages… and so much more.

Installing
Installing Piwik on Dreamhost is really simple: just go to the goodies section on Panel and use the One Click Install.

Pausing
You must wait for the email notification of completion as this contains the JS tracking code and admin's password.

Troubleshooting:
Piwik has trouble with generating stats with some CMS applications such as vBulletin. The issue appears to be caused by conflicting JS files. JS files are used in the tracking code that you add on the pages you wish to receive stats for. A solution seems to be to use "literal" tags. You can read about this here:

http://forum.piwik.org/index.php?s=23d7420862445bca50231b3e81bc4287&showtopic=4281