Who wrote that joke?

If you assumed the folks listed in the credits as writers on "Late Show with David Letterman," "The Tonight Show with Jay Leno" and other late night chat shows are the ones who come up with all the gags you hear in the host's monologue, think again. This fascinating piece from the L.A. Times discusses the underground world of freelance joke writers: "an underground network of comedy writers who supply the late-night programs with a constant stream of material. If one of their jokes gets on the air, they get a check for $75 or $100. What they don't get is any credit or union pay."

Conan O'Brien is one of the few late night hosts who does not use freelancers, and the article says he will continue that practice when he starts hosting "The Tonight Show" next month.