Here's a fun list from Wired of "100 Quotes Every Geek Should Know"
Most of the ones you would expect to be on there are on there. Here are a few favorites I find myself using that aren't quite as ubiquitous:
“Greetings, programs!” -Flynn, TRON
“If we knew what it was we were doing, it would not be called research, would it?” - Albert Einstein
“Okay. You people sit tight, hold the fort and keep the home fires burning. And if we’re not back by dawn… call the president.” - Jack Burton, Big Trouble in Little China“Oooh, ahhh, that’s how it always starts. Then later there’s running and screaming.” - Ian Malcolm, The Lost World: Jurassic Park