Same idea as Greg Reinacker’s aforelinked plugin, except Tyler Hall’s will notify you based on certain domains showing up in your referral’s list (such as Digg, Slashdot, and Daring Fireball):
Why the name Holy Crap!? Because that’s generally the first thing you say when your website hits the front page of Slashdot.
And coincidentally, today is the 3rd birthday of Tyler’s plugin.