FnordMetric is a highly configurable realtime app/event tracking thing based on ruby eventmachine and redis.

Looks to be like an open-source version of Google Analytics - it even gives you a live dashboard view of your data. The big differences seem to be:

• It appears to be much more configurable than Google Analytics - you define (in your code) the metrics to capture and visualise. This does mean that it is much more coupled to your application and may make it more difficult to use it across projects.
• It’s open-source.

I like the idea but, for me, the first point is a bit of an issue. I’d like this kind of thing if I could use it without tying it (directly) to my application. Perhaps I could hack that together myself though… ;)