*NLP Toolbox
  CLT http://complingone.georgetown.edu/~linguist/compling.html
  GATE http://gate.ac.uk/
  Natural Language Toolkit(NLTK) http://nltk.org
  MALLET http://mallet.cs.umass.edu/index.php/Main_Page
  OpenNLP http://opennlp.sourceforge.net/

*English Stemmer
  Snowball http://snowball.tartarus.org/

*English POS Tagger
  Stanford POS Tagger http://nlp.stanford.edu/software/tagger.shtml
  TreeTagger http://www.ims.uni-stuttgart.de/projekte/corplex/TreeTagger/
  TnT http://www.coli.uni-saarland.de/~thorsten/tnt/

*English&Chinese Parser
  Stanford Parser http://nlp.stanford.edu/software/lex-parser.shtml
  Berkeley Parser http://nlp.cs.berkeley.edu/Main.html#Parsing

*English Keyphrase Extractor
  KEA http://www.nzdl.org/Kea/index_old.html
  
*English Name Entity Recognizer
  Stanford NER http://nlp.stanford.edu/software/CRF-NER.shtml

*Chinese Word Segmentator
  中科院ICTCLAS http://www.nlp.org.cn/project/project.php?proj_id=6
  Stanford Word Segmenter http://nlp.stanford.edu/software/segmenter.shtml

*Topic Modeling Tools
  Matlab http://psiexp.ss.uci.edu/research/programs_data/toolbox.htm
  GibbsLDA++ http://gibbslda.sourceforge.net/
  GLDA http://code.google.com/p/glda/

*Conditional Random Fields
  FlexCRFs http://flexcrfs.sourceforge.net/ 含有MPI并行版本。
  CRF++  http://crfpp.sourFceforge.net/
  CRF Package http://crf.sourceforge.net/
  CRF Matlab http://www.cs.ubc.ca/~murphyk/Software/CRFall.zip
  CRFSuit http://www.chokkan.org/software/crfsuite/
  SGD with CRF http://leon.bottou.org/projects/sgd
  HCRF http://sourceforge.net/projects/hcrf/

*Support Vector Machine 
  LIBSVM http://www.csie.ntu.edu.tw/~cjlin/libsvm/
  LIBLINEAR http://www.csie.ntu.edu.tw/~cjlin/liblinear/
  Pegasos http://www.cs.huji.ac.il/~shais/code/index.html

*Search Engines
  Lucene http://lucene.apache.org/
  中科院FirteX http://www.firtex.org/

*Machine Learning and Data Mining Toolbox
  Weka http://www.cs.waikato.ac.nz/ml/weka/