[anarchitect]

Looks great. Wouldn't work well for us though because our main enemy is over-aggressive spiders that don't trigger Analytics trackers.

[thruflo]

Same might apply to an overloaded api / anything not serving html pages to browsers.

Heroku provides log-runtime-metrics, which includes current cpu load / pending cpu tasks. The librato addon also shows request throughput in its dashboard UI. I'm not sure where it gets this data from. If not logging then perhaps new relic?