"Late Show" while Republican Mike Huckabee ventured across picket lines to play bass guitar and trade jokes with Leno on "Tonight." Letterman had the biggest celebrity guest, Robin Williams, who teased Letterman unmercifully about his beard, alternately comparing him to Gen. Robert E. Lee, a rabbi and an Iraqi mullah. Meanwhile, over on NBC, Leno segued from Huckabee to chef Emeril Lagasse and then the rapper Chingy. O'Brien welcomed Saget to pitch a new NBC show. Race car driver and "Dancing With the Stars" champ Castroneves came to Kimmel. Craig Ferguson appeared with no guests but a full complement of writers on "The Late Late Show" on CBS; his show is produced by Letterman's company, Worldwide Pants, which struck a separate deal with the guild. "I just want to send a message to the D-list celebrities of Hollywood," Ferguson said. "You're still welcome here." Creative stretch marks were immediately evident on the shows without writers. O'Brien, sporting facial growth to match his red hair, showed off Christmas cards, danced on his table as his band played the Clash's "The Magnificent Seven" and tried to see how long he could spin his wedding ring on his desk. Leno took questions from his audience. There was also plenty of free on-air promotion for the guild's cause. "The writers are correct, by the way. I'm a writer ... I'm on the side of the writers," Leno said. "I want to make this clear. I support their cause," O'Brien said. "These are very talented, very creative people who work extremely hard. I believe what they're asking for is fair." Letterman brought writers on to recite a top 10 list of their strike demands. They included "complimentary tote bag with next insulting contract offer" and "Hazard pay for breaking up fights on `The View."' "You're watching the only show on the air that has jokes written by union writers," Letterman said. "I hear you at home thinking to yourself, `This crap is written?"' Not all the hosts were as charitable. During his opening, Kimmel criticized WGA members picketing Leno and O'Brien: "I don't want to depart too much from the party line, but I think it's ridiculous. Jay Leno, he paid his staff while they were out. Conan did the same thing. I don't know. I just think at a certain point you back off a little bit." Huckabee appeared on Leno despite his apparent confusion about the strike and a bid by picketers to keep him away, and Clinton taped a cameo introducing Letterman. "Dave has been off the air for eight long weeks because of the writers strike," she said. "Tonight, he's back. Oh, well, all good things come to an end." Huckabee said he supports the writers and did not think he would be crossing a picket line, because he believed the writers had made an agreement to allow late-night shows on the air. But that's not the case with Leno. "Huckabee is a scab," read one picket sign outside Leno's Burbank, Calif., studio. The writers guild urged Huckabee not to cross their picket line after he flew out to California. "Huckabee claims he didn't know," chief union negotiator John Bowman said. "I don't know what that means in terms of trusting him as a future president." For fans of the late-night hosts, the controversy was secondary to seeing their favorites again. Chuck Gunther of Grand Junction, Colo., stood on a sidewalk outside of Letterman's New York studio on a frigid night hoping to get into the audience. "When Dave is live," he said, "it's fresh and new every night - instead of watching reruns of `Seinfeld."' ABC reporter Linsey Davis has more.