NYPD
The NYPD's site is one of the worst city government sites on the web. You'll be hard-pressed to find any useful data on the site, but you can view precinct maps, and find contact information.

Amnesty International's Report on Police Brutality in New York

Federal Crime Statistics
There are essentially two types of crime statistics that the federal government keeps. The FBI's Uniform Crime Report, which aggregates crime data from every police department in the country, is the most comprehensive and in-depth statistical resource availble in terms of crime data on the web. However, due to the fact that many crimes go unreported, the Bureau of Justic Stastistics conducts annual Crime Victimization Survey. Using a sample of citizens from differnet areas of the country the survey attempts to ascertain the levels of crime victimization. For more information about the difference between the two measures, check out the BJS's info sheet.

FBI UCR
BJS Victimization Survey
Drug Efforcement Agency

APBnews.com
This is a sight with all things crime and criminal justice related. Their resource center provides some useful links however, their "crime-risk" statistics should be taken with a large grain of salt, since the figures don't have anything to do with actual crime data but rather, use census demographic information to calculate the risk of crime.