Site Monitoring is a Java-based tool which provides various ways to monitor websites and their content.
Launch the program and it opens a page in your default browser. Clicking "Checks" displays a couple of sample site checks to help you figure out how everything works.
The first, "javavids homepage", by default regularly checks the availability of http://www.javavids.com, plotting the results on a graph.
Click "Edit" and you can customise this by setting a new URL, checking that the page contains (or doesn't contain) a text string, telling the program to look for broken links, setting timeouts and schedules, and optionally setting up email notifications of any problems.
The second example, "sqlvids sitemap", expands on this by checking all the page links at http://www.sqlvids.com/sitemap.xml.
Again, you can tweak the example's settings to see how they work, or just add additional checks for sites of your own.
Site Monitoring's interface is a little more cumbersome than a native application, but it's not difficult to figure out how everything works, and there's enough configurability here to make it useful.