Aw, c’mon, I got two…
K: “That was turbulence, caused by the crossing of a boundary layer.”
S: “The boundary between what, Mr. Spock?”
K: “The boundary between where we were, and where we are.”
Harry Mudd: “Do you know what their penalty for that is?”
Spock: “The convict gets his choice of death by hanging, death by phaser, death by poison, death by…”
Tom Paris to Harry Kim, as I recall…
Best. Episode. Ever.
Also great is Sisko’s closing speech:
Even his o-ver-e-nun-ci-a-ting worked to good effect there
McCoy, at the end of “Journey to Babel” (maybe a slight paraphrase):
“What do you know! I finally got the last word.”
“No tribble at all.”
Scotty’s (purportedly) ad-libbed remark to Kirk at the end of “Trouble with Tribbles.”
What? No one’s mentioned it yet?
“To boldly go where no one has gone before”
Of course, there’s my favorite “how the hell did that get past the censors” line:
TOS: “Mirror, Mirror”
Mirror-Marlena: I’ve been a Captain’s Woman, and I like it. I’ll be one again if I have to go through every officer in the fleet.
Kirk: You could.
And a nicely chilling understated line from the same episode:
Mirror-Spock: If I am successful,you see yourself a step nearer to the captaincy. I do not want to command the Enterprise, but if it should befall me, I suggest you remember that my operatives would avenge my death,… and some of them are Vulcans.
I always wanted to see Bones standing in front of a mangled man saying, “Dammit, Jim, I’m a doctor not a… Oh, right!”
However, it leads me to a favorite line, if not necessarily the best line, “Dammit, Jim, I’m a doctor, not a bricklayer.”
And what a priceless look on Mirror-Sulu’s face!
I love Italian. And so do you.
ST: Insurrection
From TOS’ Friday’s Child:
Dammit, I’m a doctor, not an escalator!
Seven of Nine, to Harry Kim: “Do you wish to copulate with me?”
A favourite if only because of the sure and certain knowledge that there were millions of HTG*s at home all going “Me! Me! Pick me!”. 
(*Horny Trek Geeks)
The user Khan has this in his location:
This is Ceti Alpha V!!!
Bleurgh, I hate that line. A rip off from TUC, as bad as reusing the frelling BOP exploding in Generations :rolleyes:
And damn you for quoting it, its my favourite quote and brings a lump to my throat when I watch the episode :mad:
What does Spock say upson his return to the ship?
JIM! Er, Captain. You seem…uninjured.
JIM!
Er, Captain. You seem…uninjured. :dubious:
Done in an SNL sketch where the enterprise is coverted into a revolving restraunt. Some one begins choking and Kirk (Shatner) calls out “Bones help that man.”
“Damn it Jim I’m a Doctor… Oh…”
Best moment Dana Karvey as Khan trying to defeat Kirk with the use of a Health Inspector.
Oh yeah lines…
“Oh, now he’s doing a Count Down!” (The Corbomite Maneuver)
“No more Blah blah blah!” (Miri)
“I heard it was similar” (Kirk comparing to the Roman Gladitoral TV shows to Old Earth Television Bread and Circus)
"For one I’d like to come down to a planet and say "Behold I am the Arcangel Gabriel "
“Domo arigatu, Mr. Mugatoo”
Bones to Spock, “Are you out of your Vulcan mind?”
Not the deepest line in ST-land, but one that I use quite often 