Very nice Rated 4 out of 5 stars

Very nice. But the notification pop-up should have an option to stay open until clicked away ...for the time when you are away from the computer and won't hear the sound either.

If someone needs a browser-independent software that does about the same (it can't highlight selected text though and is a bit akward to set up) and that works even if the browser is not running, have a look at "WebMon" (http://tinyurl.com/ycyyf6).

This review is for a previous version of the add-on (0.12.1).