So many of my favourite lines have already been mentioned by all of you guys.

But here are some others I like.
-Ennis wrote back,
You bet...
-"I figured you was sore from that punch".
Ennis' euphemism for "sorry". His remorse really comes through, touchingly, in that terse line.-"Listen. I'm thinkin, tell you what, if you and me had a little ranch together, little cow and calf operation, your horses, it'd be some sweet life..."
Aw, the wistfulness of it all. I would have loved that for them, but alas...
-Years on years they worked their way through the high meadows and mountain drainages, horse-packing into the Big Horns, Medicine Bows, south end of the Gallatins, Absarokas, Granites, Owl Creeks, the Bridger-Teton Range, the Freezeouts and the Shirleys, Ferrises and the Rattlesnakes, Salt River Range, into the Wind Rivers over and again, the Sierra Madres, Gros Ventres, the Washakies, Laramies, but never returning to Brokeback.
-...so what we got now is Brokeback Mountain. Everthing built on that...
-"You got no fu**in idea how bad it gets. I'm not you. I can't make it on a couple a high-altitude fucks once or twice a year. You're too much for me, Ennis, you son of a whoreson bitch. I wish I knew how to quit you."
(Incidentally, I particularly dig "son of a whoreson bitch" heehee
)
-Like vast clouds of steam from thermal springs in winter the years of things unsaid and now unsayable -- admissions, declarations, shames, guilts, fears -- rose around them. Ennis stood as if heart-shot, face grey and deep-lined, grimacing, eyes screwed shut, fists clenched, legs caving, hit the ground on his knees.
Pure, unvarnished Ennis anguish we have here.....Dang, I've been busted slacking off at work.

Will have to resume this later, as there are so many more lines... Perhaps I should just copy and paste the whole short story?