NowComment has the most sophisticated collaboration tools available for group discussion, annotation, and curation of texts, images, and videos.
It displays threaded commenting alongside the sentences and paragraphs of texts, the areas of images, and timestamps of videos to create engaging online conversations literally in context. Brainstorm, debate, and collaborate as never before!
Y. Mor, J. Tholander, and J. Holmberg. The 10th Computer Supported Collaborative Learning (CSCL) conference (2005), page 450 - 459. Taipei, Taiwan, Lawrence Erlbaum Associates, (2006)