I find it hard to believe that memosnag is not in this list. memosnag is the best bookmarking app out there, period. First of all it’s 100% free. I use it bookmark webpages but also save images, text selection, YouTube and Vimeo videos. It’s great for school because it creates citations for everything you bookmark. I also find the folders organization unbeatable and I have full control over privacy settings. And again, it’s 100% free.