I've been using Google Alerts to monitor for drug and gambling spam placed into compromised user accounts for a while. If you're a provider of web space for any reasonably sized organization, or if you have the ability to publish web pages and want to monitor the, Google Alerts can be a great way to add an additional layer of defense.
To build an alert, simply identify common key words from the sites, then add them to an alert. You'll note that I remove PDF, PowerPoint, and Microsoft Word .doc files by default, as those are often used in research or presentations.
You can use anything you can do via the normal Google search syntax, allowing you to create reasonably powerful tripwires.
site (your site) -pdf -ppt -doc "poker" or "xanax" or "viagra" or "cialis"Once you've built your alerts, build a filter for them, and check the folder. Don't forget to set your alerts to plain text mode in your preferences if you want to view them more easily.