With the release of iOS 7.1, Apple added a new viewport meta tag to Safari. The minimal-ui  tag lets us minimize the top and bottom bar in the browser interface, which gives us more screen real estate and creates a much more cleaner look.

Here’s how you implement it:

<meta name="viewport" content="minimal-ui"/>

And here’s a comparison how it looks with and without the meta tag:
minimal-ui

If you want to see the bottom toolbar, you just click in the adress field.

Update

As of iOS8 , this feature has been unfortunately been removed and is no longer supported.