As there is a lot of discussion and concern about Google Analytics (specially here in Germany), we chose to host our own site statistic tool. We are using the open source tool piwik for some time now and are very happy with it. It does not only comply with the very strict german privacy law (i.e. it does not store ip addresses), but also is very good to use. After the last update, our small vServer could not cope with the number of users anymore and went unreachable.
So we moved it to our main server which is completed now and it seems to work just fine. Some numbers: The Database size exceeds 17 GB and we have more than 2 million unique visitors per month. So it is not too surprising that the old server was not strong enough.
Also, you can now opt out of the the tracking. If you should want to do so, you can do this on the contact page.