Best Kiss
Although I'm a slasher and would love to see Gibbs/Tony or Tony/McGee in the show, it will never happen, and my fave het couples would be Tony/Abby (because although I think they are BFF's, I think they slept together) or McGee/Abby.....and they haven't done anything on screen. So my favorite would have to be whenever Gibbs kisses Abby on the cheek, I think it's sweet :)
Saddest Moment
I think the saddest moment has to be is whenever Gibbs is remembering Kelly. The expression of pain that Mark Harmon has whenever she is mentioned is heart-breaking!