User: l-carnitine

Re:Yes it's a dupe, but lets get something straigh

On: Text-Mining Technique Intelligently Learns Topics

The evaluated http://gate.ac.uk/ which is GPL software but ended up using http://search.cpan.org/~acoburn/Lingua-EN-Tagger/. There are several other tools in this space that can be glued together to create this type of software:

http://www-nlp.stanford.edu/
http://tcc.itc.it/research/textec/tools-resources/ jinfil.html
http://wordnet.princeton.edu/
http://www.alias-i.com/lingpipe/web/faq.html
http://www.isi.edu/licensed-sw/halogen/index.html

Not trivial, but if you wanted to DIY, you don't need to start from scratch. Though, having a bunch of hardware to chug through 1000s of documents would still be needed :).