Our mail server just wigged out and stopped sending emails. FogBugz didn't like this and began posting notifications about its inability to send mail. By the time the problem was resolved there were about 125 notifications on the Notifications page. Much to my disappointment, I discovered there is no way to dismiss them all with a single click.
Fortunately, I found this script to automate the process of cleaning up all those notifications. Nevertheless, how about making it easier by adding a button to the Notifications page that dismisses them all?