Annotation web site

Just wanted to let people know about a web site that lets you add annotations to any document. See http://www.cruxlux.com/annotate . It is useful for remote teaching and learning, or just for your personal interest. There are things like Hamlet's soliloquy up but you can also paste in any text you want. It could be good for either commenting on students' writings, or for giving them reading material to ask questions about.