Christine Hauser reports in the New York Times that the NYPD made 171,094 stops in the first three months of 2009.
Unlike many, I don't think stop and frisks are inherently bad (not all that were stopped were frisked, though I'm sure many were). I'm willing to concede that aggressive stop and frisks most likely contributed to making New York a much less violent city.
BUT... there's a big difference between a smart officer with reasonable suspicion making a stop because he or she is suspicious and a lazy officer making a stop because he or she needs to meet an arrest quota and can kind of B.S. the reasonable suspicion needed to justify the stop. You stop enough people and one will eventually be wanted on a warrant.
We can (and should) debate if stop and frisks are necessary and effective. But I don't think that even the NYPD would argue that bad stop and frisks are good. If an officer can't naturally make an arrest and write a few citations a month in a high-crime district, it's probably better to have that officer do not much at all.
A quota doesn't teach officers to police smarter. Quotas don't make good officers work more. Quotas don't effect good police. Quotas make not-so-good police officers police more. They make lazy or bad officers do more lazy or bad things. And bad stop and frisks piss people off who should and otherwise would be supporting police.
Instead of worrying about the number of stop and frisks, we should worry about the quality of stop and frisks. That's harder to quantify. But deemphasizing "productivity stats" is a good place to start.