In most browsers, you can middle click on a non-link to enable auto-scroll:
i.e. you middle click and this icon appears, then the page auto-scrolls in whatever direction you move your mouse. This is useful for creating a slow-scrolling screen for reading longform text, like a teleprompter. If configured properly (where moving the mouse further from the autoscroll icon increases speed), it is also a convenient way to scroll large distances quickly.