A Chrome extension let's you switch from one user agent to another in just a moment

An extension called "User-Agent Switcher for Chrome" makes it easy for Chrome Web Browser users to switch from one user agent to another.

In other words your Chrome can pretend to be IE or Firefox. Android browser, Windows Phone IE and iPhone/iPad Safari are supported as well.

Why would you change your user agent settings in Chrome? Well, for example you might need a quick check to see how your mobile web site looks like.