I tried out statsd + graphite and it's flexible, but it requires a ton of dependencies (python, django, apache, cairo, sqlite, and node.js) and needs a lot of configuration across a bunch of apps to get up and running. It might not be too bad if you have a django app, but there was very little overlap with my stack so I decided against it.

It would be nice if the whole thing could be rolled up into a single config file and one node.js app that forked two processes for web UI and stats collection. And cairo could be replaced with javascript+canvas or svg on the client side.