http://www.exceptionhub.com/
This link is now broken.
about:
* Logs all JavaScript errors (local or remote)
* Provides a stack trace to find the cause in all browsers
* Groups errors by cause
* Development and Production modes
* RSS feeds for errors
Bouncer is a real time statistics and security engine written in PHP5. It analyses the browser or bot version, and detects eventual bad behaviors in order to prevent spam.