Do you know any website that uses this "sticky sidebar" principle?

I'm looking for an alternative to having a scrollbar within a page with a sidebar (as on Youtube, Gmail...).

I'd rather do something like this : sticky sidebar

The idea is that if the content of the left sidebar is shorter that the height of the window, it will be "sticky", thus always visible. However if it's longer than the height of the window, it will scroll at the same time at the main content area, up to a point.

I'm looking for websites that use this kind of pattern in order to present this idea to a client. Facebook does this but I'd rather find another example that doesn't require logging in.