if you like Wikipedia as your "ontology/vocabulary" there is a task in NLP which is called Wikification. A demo online of one of the most recent approaches is here: http://tagme.di.unipi.it/

I REALLY need real-time. I was thinking "spell checker" with NLP-driven recommendation and ties into ontologies with thesaurus capabilities. I would damn surprised if no one wrote such a tool yet.

Well, be damn surprised :) as it is a difficult problem due to the ambiguity of the language.

some videos here about conception and inferences http://www.youtube.com/jaguaracisilva

Try the following links:

http://cogcomp.cs.illinois.edu/demo/pos/?id=4

http://cst.dk/online/pos_tagger/uk/

http://nlp.stanford.edu/software/tagger.shtml

You could also check bioportal annotator web service (http://bioportal.bioontology.org/annotator) for a set of biomedical ontologies