Yesterday's BC said it best, "That's why nitpicking is number 1!"
"We have met the enemy, and he is us." - Pogo
Possibly the most resonant comic-strip quote of all time.
"Of all the Charlie Browns in this world...you're the Charlie Brownest." - Linus
Of course, practically every Peanuts strip can be mined for quotes - but this one just sorta sums it all up to me.
"Show me a good mouser, and I'll show you a cat with bad breath." - Garfield
In response to Calvin's question about what happens when we die:
"I think we play saxophone for an all-girl cabaret in New Orleans." - Hobbes
From Peanuts: Linus observes "There's no heavier burden than a great potential".
Ah, but Calvin's reply (to the all-girl cabaret) is classic as well... "Do you mean if we're good or bad?"
The comic Get Fuzzy is responsible for one of the all-time great exchanges:
Bucky: Man, this meatloaf really-
Rob: Hey! Watch it! This is my mother's recipe.
Bucky: Um... well... this meatloaf does what a vacuum does.
Rob: That's it!
Satchel: This meatloaf runs the FBI?
Get Fuzzy is probably one of the funnier strips out there. When I get more time I'll start a thread for it.
Going through the book 100 Years Of American Newspaper Comics have come across two quotes I like.
The Bungle Family (1918-1945)
George Bungle: The way I look at neighbors, never hit them with your fist unless they grab the club out of your hand.
Having had the misfortune to have neighbors I can fully sympathize with that.
Buster Brown (1902-1926)
Buster: There's too much seriousness loose on the market now.... I am going to laugh and work overtime at it.
Here's a couple of my favorite Peanuts quotes:
"I love Mankind! It's people I can't stand!" - Linus Van Pelt
"I gave up trying to figure people out. Now I let them try to figure me out." - Snoopy
I like those. 
Thanks.
Sorry about reposting from athoer board, but...
The Boston Globe carries it. On Friday March 7, 2003. Rob and satchel are discussing signs of the apocalypse. Satchel claims a Red Sox and Cubs World Series. As a nit picker and Red Six fan I feel I must point out the Red Sox appearing in the World Series is not a sign of the apocalypse. The Red Sox winning the World Series (out right not like the 6 game tie in 1975) is a sign of the apocalypse.
I don't have the books handy for reference of the exact quote, but I remember a Calvin and Hobbes strip wherein Calvin is talking to Hobbes: "I had a good idea once, but it never took off. In fact, it didn't get on the runway. I guess you could say it blew up in the hanger." (Hobbes replies "Your ideas do tend to do that.") That quote pretty much fits me.
One of Snoopy's more memorable attempts at literary romance:
It was an enchanted evening...Two strangers across a crowded room.
They never meet.
The room was too crowded.
Oh, and one more Snoopy gag:
WWI Flying Ace, trotting happily down the road, busting into a song to pass the time:
"It's a long way to -"
Notices signpost: 'Tipperary, One Block'
WWI Flying Ace:
"<Sigh...>"
I saw that Tipperary one just recently. That was a classic one.
I've just read this one from "Calvin and Hobbes": "I let my mind wander and it didn't come back."
http://www.ucomics.com/calvinandhobbes/?uniq=1639
Look for the July 19th, 1992 strip.
Calvin: "Good heavens, I think I blew my face inside out!" -Calvin and Hobbes
A cow (eating a steak): "Hey, we taste kind of like chicken" - The Far Side
Then there's the great Dilbert in which our hero's unnamed date complains about having to take a class to work her computer because she "doesn't have time" to read the instructions:
Date: "I'm cold"
Dilbert "You should try jackets, they're terrific"
From Get Fuzzy:
Bucky Katt: "Work? What do I look like, a border collie?"
Rob: "Aaaaand your fear of the government would be...?"
Bucky: "Well, cloning! Obviously! I mean, look at me, I'm gorgeous!"
Bucky [standing at attention in front of the kitchen counter, paw on heart]: "I pledge allegiance to the can/Of the perfect food which is tuna/And to the fishy for which it cans/One portion, just for me/With olive oil/And crackers on top."
Peanuts:
Snoopy [shaking his fist at the sky]: "Stop snowing on my secretary!!"