I'm a big fan of the NewRelic monitoring system, and we use it for monitoring both EDU 2.0 sites. I honestly can't imagine running a Rails site without a monitoring system, and NewRelic is the best. If you're interested, here are some screen shots of the system in action. Click a picture to enlarge it.
Overview (average request times, throughput, appdex score)
Web transactions (throughput, response time, longest operations)
Database transactions (throughput, response time, longest operations):
Transaction traces (details of the longest transactions, including full SQL)