The +Google Analytics team just launched Content Experiments, which helps you run experiments on your website to see what page content and designs are most effective. With the help of a setup wizard, you can develop several versions of a webpage, each of which will be shown to different visitors. Analytics then determines which one of those versions is best for your site. (Some of you might recognize this functionality from Website Optimizer, which is now being rolled into Analytics.)

Find more info on the Google Analytics Blog:
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