Naturally, on OS X, where scroll events are already inertia-ed by the time they reach the browser, this makes scrolling way too fast. As a bonus, it breaks the two-finger back/forward gestures, as well as cmd-{up, down} to go to the top or bottom. How nice...
That browser extension already exists, see https://github.com/defunkt/dotjs there are forks for other browsers and OS'
Looks like it's nicescroll[0], a jquery plugin (!!!).
If you had a browser extension that allowed you to execute js on each page you visited, the plugin can be turned off if you define `$.niceScroll = true`.
Maybe I should write that one day.
[0] https://github.com/inuyaksa/jquery.nicescroll