There are quite a few efforts out there. Someone has already mentioned rbutr (actually my personal project) - you can view it in action without the plugin by ju

There are quite a few efforts out there. Someone has already mentioned rbutr (actually my personal project) - you can view it in action without the plugin by just adding rbutr.com/ to the front of any URL, eg: http://rbutr.com/http://www.realfarmacy.com/johns-hopkins-scientist-reveals-shocking-report-flu-vaccines/ http://rbutr.com/http://www.realfarmacy.com/johns-hopkins-sc... However rbutr isn't really what you've described here. What you've described is either https://hypothes.is/ https://hypothes.is/ or http://fiskkit.com http://fiskkit.com or https://factlink.com/ https://factlink.com/ Oh, also, Hypothes.is had previously put together this spreadsheet on Google Docs which lists all of the previous efforts to make web annotation applications. It hasn't been kept up to date though so I keep a local one up to date now, just in case this is ever lost: https://docs.google.com/spreadsheet/ccc?key=0Aujm_HldNh4WdHJrcTNIZ2tOQWhETjNDMGdkRjZEVGc#gid=0 https://docs.google.com/spreadsheet/ccc?key=0Aujm_HldNh4WdHJ...