I've been doing nothing but raving about Overheard In New York, a blog that chronicles the various things its submitters have overheard being said at various places in the city.
For example, from a recent post:
Street Preacher: Have you found Jesus?!
Guy #1: Why? Did you lose him?
Street Preacher: Have you found your Lord, our Savior, Jesus Christ?
Guy #2: Next time, try using better fucking nails!
--42nd & 8th
The best part about these quotes is that in almost every case, you can just "see" the people in question who are saying these things.