Pearltrees now allows you to organize collections of links, videos, images, and files. The Pearltrees browser extension allows you to quickly add content from a web page to your collections (bookmarking in a visual format). To combine folders or create sub-folders simply drag and drop one folder on top of another just like you do when making folders of apps on an iPad.
The extension also works on your iPad the same way in your web browser by a free iPad app.
The add button allows for your to add a collection, a website, note, pictures or files.