It's not a shake effect, but a scroll effect (jQ scroll-to plug-in). The appearance of shake occurs because the scroll rate is higher than your browser can render smoothly.

The site uses a paginated, single-page model with sections styled with significant design differences for each "page". When clicking a link (they're not actually links [boooo!]), a JS scroll event is triggered. Some relatively straight-forward tweaks could fix this.

The author uses span tags to wrap elements that act like links. A far more appropriate markup would use an anchor tag with a fragment identifier (#fragment-id). The span tags that are currently in use use class names to identify the "location" of the target. This is, again, poor form. A URL is the tool for specifying location, and URLs are linked using the anchor tag.

HTML Excerpt 1:

<div class="wrap"> <span class="scroll_to_text">Text Scope</span> <p>Compare text and source code.</p> </div>

Change to:

<div class="wrap"> <a href="#text">Text Scope</a> <p>Compare text and source code.</p> </div>

JS Excerpt 1:

$(".scroll_to_text").click(function() {$.scrollTo($("#text").position().top-40, 300)});

Change to:

$("#text").click(function(event) {$.scrollTo($("body").position().top, 300);event.preventDefault();});

I'm a novice HTML/Javascript guy at best, so the code above may not function correctly in production, but I'm certain that the principle is appropriate.