A 'comical robot' that provides relief during uncomfortable silences in conversations was demonstrated at SEMICON Japan 2008.
(Comical robot aids conversations)
When you are talking with another person, the robot is listening for a break in the conversation. When you say "Ahhh" or similar sound, the robot tries to provide some comic relief.
People laugh when they feel like something is funny, and this laughter makes conversation between people more comfortable. Conversations also tend to be more stimulating when laughter is involved, so we're researching robots that will help improve conversation in this manner.
Take a look at the 'comical robot' on this video; start at about 1:10 to skip to the relevant bit.
('Comical Robot' video)
I've tried to think of a robot comic, a mechanism that specifically entertains with jokes, but can't think of a reference. Readers?
Update 17-Jun-2012: Take a look at the robot comedian from William Tenn's 1951 short story The Jester.
End update.
Of course, the idea of using robots as comic relief in films is old hat; C3PO from Star Wars is a good example.
A Remarkable Coincidence
'There is a philosophical problem of some difficulty here...' - Arthur C. Clarke, 1953.
Technovelgy (that's tech-novel-gee!)
is devoted to the creative science inventions and ideas of sf authors. Look for
the Invention Category that interests
you, the Glossary, the Invention
Timeline, or see what's New.
Boy Makes Biomimetic Turtle Robot
't came out into plain view. Darkington glimpsed a slim body and six short legs of articulated dull metal.'
Elon Musk Wants Data Centers In Space
'Internally it’s made up of millions of components, but the most important ones are the thinking and memory parts of the Mind proper.'
Origin F1 Humanoid Robot's Facial Skin
'I could look down at that face of carefully molded synthetic rubber, tinted the exact shade of the doctor's living flesh.'