Where can I find a map of zip codes?

I want a free map of Brooklyn (and other areas if possible) that I can print out, showing exactly where zip codes begin and end- exactly from which street to which street. I need it for letters I'm sending out to many people (mostly in the Brooklyn area) and I don't have their zip codes. I want to be able to easily look at a map and see which zip code would be the right one for that specific address. Thanx!|||http://www.unhp.org/crg/indy-maps-bkzip.鈥?/a>|||Go to USPS.gov they have a good one there.