Specto é exatamente o que você está procurando!
Instale-o com:
sudo apt-get install specto
Descrição:
Unobtrusive update notification program
Specto is a desktop application that will watch any user-specified events
(web, folder, ...). This will allow users, for instance, to specify a website
to watch, and Specto will automatically check for updates on the web page. It
will then notify the user when there is activity. This will allow the user to
be informed of new updates/events instead of having to look out for them.
Imagens:
