John McTaggart Ellis McTaggart (yes, double McTaggart) was an idealist metaphysician, concerned with the fundamental nature of being and the world that encompasses it.
This McTaggart is only concerned with understanding Umbraco content.
McTaggart extends the default Umbraco tag property editor to use the Open Calais API to generate tags from HTML strings. Don't think about tags for your content, just hit the button and let McTaggart do the hard work - he lives for it!
Allowing content creators to add their own tags or keywords is fine, except you'll end up with a tag set representing what the author thinks they've written about - McTaggart, by way of Open Calais, analyses the text to return tags that relate directly to the content and can thne be used to generate more accurate search result sets.
McTaggart is a simple property editor - add it to an Umbraco project, create a datatype using the McTaggart editor, add your API key (available at opencalais.com) and the aliases of the properties to analyse, and you're good to go.
v1.1: I've removed the ability for users to add their own tags - allowing that pretty much defeats the purpose of the package, which is to apply accurate tags without users having to actually think about anything. Just click a button and it's done. Also adds a config option to set the maximum number of tags to return, improves the UI for instances when there is no content available for tagging and removes cases sensitivity when looking up properties to tag.