How to use Google Alerts to find out if your site gets hacked on Blogstorm is a few weeks old now, but it's a great idea which will only take you a few moments to set up. Now.
The theory is this: if someone hacks into your website (and don't think it can't happen), it's quite likely they'll put all sorts of spammy stuff on it like ads for certain pharmaceuticals. Naturally, your site won't have those words on it. So set up a "Google Alert" (you do use Google Alerts, don't you?) which will email you if ever certain words appear on your website. The key is to add the term "site:www.yoursite" to the search term on the Google Alert. Neat.