I'm not quite sure how to get it to work though. I'm using Firefox. I got it to work but then I surfed away from the page and when I came back, it had gone. I can't get it to stay.
I think I probably pasted the script in the wrong place. I put it in Tools - Web Developer - Web Console on Firefox. I'm not familiar with how to use scripts. How do you do it?
Oh, do you have the Greasemonkey extension? Get that and then restart the browser. Then paste this into a new tab and it should prompt you to install it: http://electricjonny.com/code/group_notifier-final.user.js