Lillybot is an OpenCyc-based irc chatbot. It implements a very
simple reasoning engine that works with the OpenCyc ontology,
and hooks it to a natural-language parser. It can answer simple
english questions with small simple-english replies.
Yacca is an advanced chat bot (other plugins are under development, including a command-line only version for you to interact with yacca) that is designed to resemble a human chatter as closely as possible.
AIBuddy is an artificially intelligent chatbot. Unlike other chatbots, which pattern-match the entered phrase against a database of hard-coded responses, AIBuddy actually remembers the conversation, and can respond in context.