StumbleUpon has redesigned its website and the changes are of more than passing interest.

The 'social discovery engine', which asks users to register things they like and then guides them at random through to related sites, unrolled the changes yesterday.

The alterations follow a rise in visibility for StumbleUpon. In July GigaOm reported that StumbleUpon was sending more traffic to American websites than Facebook. Its number of regular users doubled in 16 months, now totaling more than 20 million. It boasts 33 million monthly unique visitors.

So what exactly is different?

Visuals

The site has moved from the old blue, green and white logo, to a cleaner looking dark orange and white one. More importantly, the site as a whole is more visually focused. There are big, high-quality images to accompany each interest on a user's homepage and the toolbar is less obtrusive and cleaner (perhaps it owes some inspiration to the Hootsuite toolbar?). The difference in visual appeal is striking when you compare screenshots posted by GigaOm.

'Explore' box