If Python is the programming language of your choice, you might well be interested in NLTK. Corpus toolkit is a most important part of NLTK. And it comes with a corpora package which includes a licensed copy of Brown corpus (tagged), a sample of Treebank and a lot more.
Check out this page: http://nltk.sourceforge.net/
Download: http://sourceforge.net/project/showfiles.php?group_id=30982
Check out this page: http://nltk.sourceforge.net/
Download: http://sourceforge.net/project/showfiles.php?group_id=30982