I mentioned this briefly last night. It's a plugin plus a hosted
service, that collects all the exceptions from your production site.
The idea is similar to exception_notification (which emails you all
the exception tracebacks) but sends the output to a web API. Their
hosted web app aggregates the data for you, so you can see how many of
each error there are, and run metrics. Great idea.
http://www.hoptoadapp.com/
Enjoy,
Craig