Monitoring Rails+Nginx+Unicorn logs for errors?

What are some suggested methods for monitoring my production environment logs for errors?

My stack consists of Rails 3, nginx, unicorn and bluepill (which monitors unicorn). The ideal solution would notify me immediately if an err开发者_开发问答or shows up in the logs for any of those applications.

I'd start with Exception Notification. If you start getting too many duplicate error emails, then switch to something like Hoptoad.