Multiple sites can be easily configured and tracked in one central dashboard. There is more than one way to track the site visits - javascript is not necessary (but is of course the easiest way to track) With the new version 2.0, various reports can be 'widgetized' and embedded in other web pages that are not necessarily part of the main Piwik domain (i.e. you can embed live reports in a client's intranet)

I think what I like best about Piwik is the choice to use either a JS tracker or pixel tracker. The pixel tracker comes in handy if you want to track things like Craig's List posts or emails.

Free analytic tool with a lot of features such as visitor reports, keyword, marketing reporting, and a lot more. You obviously use your own data and the tool is also open source. Can schedule automatic reports.