Bevodanot is a project mainly written in JavaScript, it's free.
Bookmarklet to let you insert ^NOT anywhere on a webpage
Bev Oda ^NOT Annotation Bookmarklet
Lets you click anywhere on any webpage to add ^NOT.
The document editing power embodied in this deceptively simple tool was previously only available to Federal Cabinet Ministers and staff. Now, you can negate any statement on any web page anywhere with the simple click of a mouse.
License: GPL v3 or higher.
http://tinyurl.com/odanotapp http://adsgb02usw.s3.amazonaws.com/bevoda/BObookmarklet.html