StumbleUpon is currently testing a opt-in feature that seems to be aimed at helping user search and find web pages more easily.
The StumbleUpon dubbed the feature as "Explore Box," and, if you have opted-in to be part of the test, the explorer box can be accessed at www.stumbleupon.com/explore. It functions similarly to the search/explore box that can be enabled on the StumbleUpon toolbar, with one noticeable difference. The Explore search box shows suggested topics as you type (see image at right), while the toolbar search shows previous tags that you've used when stumbling.
When opted-in to the test, you'll also find the new Explore search box on the StumbleUpon home page (at stumbleupon.com/home), where there's also a check box that lets users save their searches into their existing list of "interests", that are usually setup when first joining StumbleUpon.
There's also a feedback link for beta participants to offer feedback.
The features is currently under test and there is no indication when the Explore Box might roll out more widely.