Hae you checked out Eliza? It's a classic example of a pseudo-AI that manages to hold a coherent conversation with the user by recognizing key phrases and asking questions in the manner of a psychoanalyst. It's actually pretty simple (we implemented a Eliza in scheme as a lab assignment at school), but very effective. I read somewhere that some people preferred talking to Eliza rather than a human psychoanalyst, because the felt the program made them more comfortable.

There is of course a perl implementation called Chatbot::Eliza. I haven't played with it myself but it looks like it could be useful for you.

Cheers,
--Moodster