Subscriber for Mac

From Charcoal Design:

Are there web sites that you check regularly to see whether there's anything new? And usually there isn't? Then you need Subscriber to check them for you.

Unlike the subscription feature in some browsers, Subscriber allows you to specify just which aspects of a web page you are interested in. So you won't be bothered by a message telling you that a page has updated every time the date changes, or the site gets a new visitor.