[bashevis]

Like others have said, Google alerts only notifies you of news articles.

My company http://www.Alertification.com takes a more general approach and alerts you when something on any public website changes. For example, you'll get an email or text message when an Amazon price drop occurs, when a college class opens up, or even when concert tickets go on sale.

[hayksaakian]

Pro tip: advertise an alert for when a popular product goes back in stock. (eg popular electronics)

I made a one off app for the nexus 4 release to account for low inventory, and got quite a bit of traffic for low/no effort.