The jQuery wordStats plugin tries to determine what a page is about by computing the density of its keywords. It uses a simple algorithm which adds a variable weight for each keyword occurence, depending on its ‘position’ in the document. There’s of course a system to exclude ‘stop words’ (frequent pronouns, prepositions, adverbs and so on).
I use wordStats and jFeed to display a list of articles related to the current document, seeRelated feeds widget.
