Over the course of seven seasons of Star Trek: Voyager, we didn't learn as much about Ensign Harry Kim [Garrett Wang] as we would have liked to. Understandably, it was an ensemble show, and the producers couldn't delve too deeply into every character. We do know that he was a "miracle baby" as his parents tried for years to have children before he was born. He played the clarinet, loved volleyball, was the valedictorian of his graduating class at Starfleet Academy, and had a girlfriend named Libby.
And then, in the Voyager episode "Non Sequitur," Kim accessed his service records, and we caught a glimpse of his middle initials: S.L. But we never learned what those stood for. In the August/September 1997 edition of Star Trek Communicator, the Magazine of the Official Star Trek Fan Club, a fan wrote in to ask about those two middle initials. Unfortunately, he learned that they didn't stand for anything as the writers hadn't officially given Kim middle names.
However, Garrett Wang had his own ideas for what his character's middle names were. He offered up Stanley Livingstone as an example, which was a combination of the last names of journalist Henry Morton Stanley and the Scottish explorer, David Livingstone. Livingstone had been missing and out of contact for over six years, and the New York Herald sent Stanley to find him. When meeting in 1871, Stanley was reported to have said "Dr. Livingstone, I presume?" There's no evidence to back that up, though, but maybe Wang just liked the story.
Wang also had a couple more possibilities for those middle initials. The S.L. could stand for either sexy lips or sushi lovin'. If either were the case, it's no wonder Starfleet wouldn't want its other officers (or the general public) knowing the names behind the initials!