A simple web analytics tool (in the modes of Gaug.es) that only collects the data that matters (no user agent, no geolocation, just pageviews and sessions) plus a way to arbitrarily score individual sessions and browse those later.

Beautiful interface, easy, simple, fast setup, no bloat in your page (you don't have to load a Javascript file, just paste a small snippet). Trackingco.de also comes with an open-source version that you can run by yourself.