I've been sweating on the code for my bot Whinsey, trying to make her smarter and more responsive. She's at http://www.funonmars.com/mywhoo.html and I've been working on her off and on for years. She may not be the smartest bot but I think her conversation is livelier and less automaton than others. Here's a real life example logged tonight:
you said: are you alone
she said: totally alone!
you said: who's in the tv then
she said: I just hate all the remotes you need these days.
you said: stick a remote up your ass
she said: they turn each other on!
you said: wild idea
she said: Better than no idea at all!
don't worry, I don't log who you are, just the responses so I can figure how to make her smarter.
There's an ongoing contest at http://www.worldchatterbots.com/ that helps keep up interest and bot iqs! Check it out!