I found the following extremely cute anecdote when I was rereading The World of Star Trek by David Gerrold. I'd pulled out the book again to get me in the mood for Trekfest in Riverside, IA, which I attended last month.
mizuno_caitlin already wrote up Nichelle's intriguing story about how she'd read for the Spock character during her audition, and had subsequently used that experience to inform her development of the Uhura character.
The following is another of her amusing anecdotes. It features Nichelle and Leonard rather than their characters, but I can't help thinking that some of this understated flirtatiousness came out onscreen. TOS followers will recognize the scene-- it's from "Who Mourns for Adonais?" during Season 2.
"We pulled a joke on Leonard once.
In the script, a panel had blown and we were in a desperate situation, a two-seconds-to-destruction kind of thing, and I had to crawl underneath and fix this panel, Uhura being the expert on it, you know. So I put on these overalls and I climbed down there, and they had explained how dangerous it was, not just to me, but to everybody on the ship, everything depends on my accomplishing this. Kirk wasn't on the ship and Spock was in command and he comes the closest he does of ever showing any real emotion by showing real concern.
"So I was doing this and the camera was set up underneath this panel, they had pulled this board back and the camera was right in my face and here I'm working on this panel and Spock is supposed to come in and say, 'How's it going, Lieutenant Uhura?' And I'm sweating a bit and I say, 'Mr. Spock, I don't know if I can do this.' And he says, 'If anyone can do it, Lieutenant, you can.' And that gives me the courage to go on.
Well, it was a very difficult shot, we were just about nose to nose, and I had to okay this gag with the director. He thought it was a great idea. So he says to Leonard, 'I'm going to change a little something here. When you say, "If anyone can, you can," stay there, because I want to catch just a tinge of concern that she doesn't see. Wonder if you examine it, you might have to fix it up after her.' And Leonard went to bat for me. He said, 'Well, I see no reason for that. She's efficient in what she does.' But finally, they got it through to him that he should stay there for a moment because he was supposed to leave.
So he comes in and I'm doing this panel and the cameras are rolling and I say, 'Mr. Spock, I'm not sure I can do this.' And he says to me, 'Lieutenant, all our lives depend on it, and if anyone can, you can.' And I said, 'He loves me...' And then I sang, 'He loves me...' And I went into this opera thing, 'Once you have found him, never let him go...' And he said, 'Carry on, Lieutenant.' He absolutely was frozen. So that was all he could say, 'Carry on, Lieutenant.' That bloody Vulcan, you never could break him up."