Annotator | Open Knowledge Foundation - http://okfn.org/projects/annotator/
«Simple javascript (+backend) library for web-annotation. Main goals were and are: * Annotation of arbitrary text ranges; * Annotate any web (html) document; * Easy to use — 2 lines of javascript to insert this in your web page/app etc; * Well-factored and library-structured — easy to integrate and easy to extend» ‎- а меня почему-то забыли