"As soon as we started programming, we found to our surprise that it wasn't as easy to get programs right as we had thought. Debugging had to be discovered. I can remember the exact instant when I realized that a large part of my life from then on was going to be spent in finding mistakes in my own programs."
Maurice Wilkes discovers debugging, 1949.

"Java is C++ without the guns, knives, and clubs"
James Gosling, co-inventor of Java

"Keyboard not found. Press < F1 > to RESUME. "
Source unknown (appears in many common BIOSes as a real error message)

"There are only 10 types of people in the world: Those who understand binary, and those who don't."
unknown

"There are only 10 types of people in this world. Those who know ternary, those who don't and those who confuse it with binary."
unknown

"A language that doesn't have everything is actually easier to program in than some that do"
Dennis M. Ritchie

"Adding manpower to a late software project makes it later"
F. Brooks, The Mythical Man-Month.

"Always program as if the person who will be maintaining your program is a violent psychopath that knows where you live."
Martin Golding

"Any sufficiently advanced bug is indistinguishable from a feature."
Bruce Brown