[last update: June, 5 2017] My next project will be a Chat Bot.. Starting points are:

• AIML (Artificial Intelligence Markup Language) standard
• https://messengerplatform.fb.com/ [from Facebook]
• https://dev.botframework.com/  [from Microsoft]
• https://www.rivescript.com/
• https://sourceforge.net/projects/chatscript/
• Chatterbot

There are also some useful softwares as a service like

• Api.ai (Google)
• Wit.ai (Facebook)
• LUIS (Microsoft)
• Watson (IBM)
• Lex (Amazon)

And  alternatives:

• rasa.ai

Useful ML libraries:

• spacy.io
• Tensorflow
• tflearn