JavaScript error reporting service with DamnIt

DamnIT is a free service that emails you when a user encounters a JavaScript error in your webpages. DamnIT makes it simple for beta testers to provide useful feedback by prompting them after an error occurs and combining their response with error message, file, line number, and back-trace information. You'll receive detailed automated error information instead of vague bug descriptions.

Link:
https://damnit.jupiterit.com/