"If you're a US senator and your sex tape is leaked, it could end your career," says Robert Thompson, professor of popular culture at Syracuse University. "If you're Paris Hilton, it makes your career."

Two years ago Red Light District, a little known video company in California, hit the jackpot when it landed distribution rights to the Paris Hilton sex tape, an explicit bedroom video shot by a former boyfriend. The DVD has sold some 600,000 copies, establishing Red Light District as the leading player in a lucrative niche of the pornography industry: a purveyor of explicit videos of famous people, sold to an eager public, often over the vehement objections of the participants.

Britney Spears

The pop singer and new mom, who has been the subject of rampant tabloid speculation over the state of her marriage to husband Kevin Federline, filed a $20 million libel lawsuit on Monday against Us Weekly magazine. The suit has nothing to do with the recent avalanche of stories questioning her marriage, though - it's over a report that she and Federline made a sex tape and were worried that it would be leaked.

Pamela Anderson

Pamela Anderson is, until now, the only A-lister to have two separate sex tapes leak: One obviously with Tommy Lee, the other with Poison's Bret Michaels.

Colin Farrell

Colin Farrell's sex tape, also starring ex-girlfriend/Playmate Nicole Narain, leaked for a short while on the Internet before being pulled.

Kid Rock

It probably doesn't surprise anyone that Kid Rock was involved in groupie shenanigans, but the emergence of a sex tape caught everyone off guard. It probably doesn't surprise anyone that Kid Rock was involved in groupie shenanigans, but the emergence of a sex tape caught everyone off guard.

Tom Sizemore

Tom Sizemore, whose reputation for drugs, booze and sex is no secret, caught another black eye when his private sex tape stash hit the Internet.

Editor: Donald