StumbleUpon added an “add to list” feature to its popular toolbar.
The new add to list 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 new redesign allows the users to browse previews of content in a somewhat Pinterest-like format.
When you click the “Add to List” button from a webpage, it will shows a screen with your lists, so you can select which one you want to add it to, or create a new one.