First of all, I like (obviously) the quote in my sig. After that:
Quis custodiet ipsos custodes? ("Who Will Guard the Guardians?")
Real Programmers Don't Document. (If it was hard to write, it should be hard to understand)
Aposiopesis makes me want to... (I think this would make a great shirt, like the ones that MentalFloss sells).
To know recursion, you must first know recursion.
Mac OS X: Because making Unix user-friendly is easier than debugging Windows.
No trees were killed in the creation of this message. However, many electrons were terribly inconvenienced.
ACK and you shall receive.
A computer without a Microsoft operating system is like a dog without bricks tied to its head.
A computer without Microsoft is like a chocolate cake without mustard.
Claiming that your operating system is the best in the world because more people use it is like saying McDonald's makes the best food in the world.
If you're not part of the solution, you're part of the precipitate.
When a cat is dropped, it always lands on its feet, and when toast is dropped, it always lands with the buttered side facing down. I propose to strap buttered toast to the back of a cat. The two will hover, spinning inches above the ground. With a giant buttered cat array, a high-speed monorail could easily link New York with Chicago.
When they broke open molecules, they found they were only stuffed with atoms. But when they broke open atoms, they found them stuffed with explosions.
Powered by Infinate Probability Drive (Engraved on my iPod)
Edit: Oops... You were looking for quotes, not great sayings. Sorry about that

Hope someone got a kick out of em' anyway...