Per the HTML5 spec, you can access elements via their id. For example, on dropshado.ws, which has markup of <section id="posts">...</section>, plugging in window.posts or posts in the console will return the HTML element.

document.getElementById('posts')
// >> <section id=​"posts">...</section>​
window.posts
// >> <section id=​"posts">...</section>​
posts
// >> <section id=​"posts">...</section>​
posts === document.getElementById('posts')
// >> true

From my brief tests, WebKit and Opera support this, not Firefox 4.

Global HTML element with ids fiddle

The good news is that this is a convenient for debugging, no need to type out document.getElementById. Bad news is that its not especially reliable. See also this WHATWG thread polluting global namespace and other concerns.