markerPen is a simple jQuery plugin to create a marker tool for a webpage.
This plugin would come handy if you are creating webpages for academic purpose where a person can mark details while reading through a huge junk of data.
jQuery.mark is a jQuery plugin to highlight text with diacritics, synonyms, custom elements, custom class names, separate word search (multiple terms), filter selectors, word boundary and iframe support. Compatible with DataTable.
jNottery is a jQuery plugin that lets you add notes and markers to webpages. All the data is encoded as a part of an URL which makes it easy to share or save.