Cleverbot - Chat with a bot about anything and everything - AI learns from people, in context, and imitates.
From Wiki: Cleverbot is a web application that uses an artificial intelligence algorithm to have conversations with humans. It was created by the British AI scientist Rollo Carpenter, who also created Jabberwacky, a similar web application. It is unique in the sense that it learns from humans, remembering words within its AI. In its first decade Cleverbot held several thousand conversations with Carpenter and his associates. Since launching on the web in 1997, the number of conversations held has exceeded 150 million.