I'm wondering if there are studies regarding bandwidth usage of websites. Most modern websites use background Ajax requests to reload content from time to time to refresh information. Of course it takes bandwidth but I would be interested in a link to a website reporting common website bandwidth usage when you keep a web page.
If you're interested in knowing how much bandwidth specific sites use, you can download the Firebug webpage debugger and use the 'net' tab to see each request your browser makes and how large the response is.
Since I started typing this message I got 3 responses from webapps.stackexchange.com and they wereneach 26 bytes.