Alicebot
"A.L.I.C.E. (Artificial Linguistic Internet Computer Entity) is an award-winning free natural language artificial intelligence chat robot...A.L.I.C.E.'s Alicebot engine utilizes AIML (Artificial Intelligence Markup Language) to form responses to your questions and inputs." Latest version of an AI BOT
http://www.alicebot.org/

Ana Nova
Virtual newsreader
http://www.ananova.com/video/

Eliza
One of the original chat bots. She is programmed to behave as a psychotherapist, and is an example of the limitations of early artificial intelligence programs.
http://nlp-addiction.com/eliza/
ELIZA has almost no intelligence whatsoever, only tricks like string substitution and canned responses based on keywords. Yet when the original ELIZA first appeared in the 60's, some people actually mistook her for human.
http://www.manifestation.com/neurotoys/eliza.php3

Rea
"...the newest generation of Embodied Conversational Agent -- "Rea" -- a life-size animated humanoid figure on a screen that can understand the conversational behaviors of the human standing in front of it (using computer vision techniques), and respond with appropriate speech, animated hand gestures, body movements, and facial expressions of its own. The architecture for this new "conversationally intelligent" agent is based on an analysis of conversational functions, allowing the system to exploit users' natural speech, gesture and head movement in the input to organize conversation, and to respond with automatically generated verbal and nonverbal behaviors of its own."

"The research version of Rea runs on a collection of five SGIs and PCs. "
http://gn.www.media.mit.edu/groups/gn/projects/humanoid/