Easily one of my favorite sites on the internet, updated constantly throughout the day, is Overheard in New York. People from all over the city send in things they hear, from conversations with bums to funny things on the subways. Absolutely brilliant. I've posted a few excerpts below.

http://www.overheardinnewyork.com

Dumb teen: Hey, look at this! It says "Train for jobs in beeyotch."
Smarter teen: Fool! That word is biotech. Why you gotta be ignorant all your life?

--1 train

Overheard by: Manhattman

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Crazy: So I had to get fillings in all of my teeth.
Passenger: Uh huh.
Crazy: But I figured, why let them do that to me after they drilled holes in my brain, ya know?
Passenger: Sure.
Crazy: But I figured, might as well! Although if they were going to fill my teeth, I'd want them to use jelly.
Passenger: Yep.
Crazy: But the guy at the counter said they were out of jelly. So I got a blueberry muffin.

--R train

Overheard by: Johnny Shizzle

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The subway doors open. A hobo enters, holding a bottle of windex in one hand and a tube of toothpaste in the other. He says: Which is the better time to read Dostyevsky? Winter?

He sprays the windex.

Hobo: Or Spring?

He squeezes toothpaste out of the tube.

Japanese girl: Spring!
Hobo: You are correct.

--F train

Overheard by: Pete Johnson

-Smithers