Update: A spokesperson for StumbleUpon tells us this is currently just a test:

“We are currently testing a bookmarklet feature with a small subset of our community. We plan to analyze the data to determine the next steps for the feature.”

StumbleUpon has a new button called “Add to List”. It’s pretty self-explanatory. It lets you add a webpage to one of your StumbleUpon lists with the click of a button.

You can get the button here.

StumbleUpon launched its Lists feature with its major design overhaul last year. If you’re unfamiliar with it, it simply lets you collect webpages that you find in topic-oriented lists. If you want to keep a list of cool Breaking Bad links, for example, you can do so (which I do).

When the redesign left beta, StumbleUpon added an “add to list” feature to its popular toolbar.

Now, the new button allows you to add content to your lists whether you use the toolbar or not. This appears to be the latest evolution of StumbleUpon’s strategy to make the toolbar less crucial to the SU experience. The redesign was a major factor in that, enabling users to browse previews of content in a somewhat Pinterest-like format.

While some of us still prefer the toolbar as a primary way of using the service, you no longer need it to get enjoyment out of StumbleUpon, and this new button only adds to that.

Once you click the “Add to List” button from a webpage, it will bring up a screen with your lists, so you can select which one you want to add it to, or create a new one.

It’s largely been a quiet year for StumbleUpon in terms of products and new features, but that appears to be changing. The company recently announced that it has become profitable, and shared some revenue numbers, then made its first-ever acquisition.

Read our recent interview with CEO Mark Bartels for more on what the company is up to.