The late-night talk host has made guest appearances on 14 shows

Movie stars may be linked by Kevin Bacon, but in the world of TV characters, there seems to be only one degree of Jay Leno. Since taking over as The Tonight Show host in 1992, the big-chinned one has made cameos on at leat 14 shows, including Mad About You (where he interviewed Murray the dog), Baywatch (in which he received the Heimlich maneuver from David Hasselhoff), and Home Improvement (where he chatted about cars with Tim Allen). His next gig will be popping in on the pilot of Veronica’s Closet, NBC’s new Thursday-night sitcom starring Kirstie Alley.

”Jay’s always been a politician,” says a Leno spokesman. ”With TV stars, it’s all about relationships. Those players will remember and appreciate that Jay helped, and think of that when deciding what talk shows to do.”

At the very least, the spots have helped Leno’s primetime visibility, yet another factor in Leno’s ascent to the late-night throne. ”The cross-pollination really helps,” says media buyer Paul Schulman, who notes that Tom Brokaw’s ratings rose after making appearances on Dateline NBC in the late 1980s. ”It would help David Letterman to do more cameos,” adds Schulman.

But don’t expect Letterman to pop up on Melrose Place anytime soon. According to Late Show executive producer Rob Burnett, the CBS host carefully doles out his appearances based on ”What’s the idea? Is it funny? Can we trust the people doing it?” The few that have made the cut include Spin City, Seinfeld, and The Larry Sanders Show. The thinking from the Letterman camp is that — ratings apparently be damned — Dave is past the point of needing to promote himself. Sniffs Burnett: ”We don’t need to be doing appearances at Chuck E. Cheese.”