Actually, Dijjer.org says,
You don’t need to install anything. Just put a file on your site as you normally do, but add “http://www.dijjer.org/get/” to the beginning of your links. …
When they click a Dijjer link, users will get some of the file from your website, but most of it will come from other people running Dijjer. That’s how you save bandwidth. And when someone clicks on the link who hasn’t used Dijjer before, they’ll get help installing it. After that, downloads happen seamlessly inside their web browser.