Specto is a little Linux application that allows you to monitor various things like websites and emails. To install specto execute following command.
sudo apt-get -y install specto
You can use specto to watch website changes on items like individual pages, feeds, images. You can tell specto to ignore something that changes on every visit by using "Error Margin" feature.
You can tell sepcto to look for changes on fixed intervals by configuring "Refresh Interval". Don't specify too little value for this setting as it will cause heavy load on server.