sends a daily email with uncaught exceptions, rolled up by exception type. very useful.

https://developers.google.com/appengine/articles/python/recording_exceptions_with_ereporter
http://blog.notdot.net/2010/03/Using-the-ereporter-module-for-easy-error-reporting-in-App-Engine