I’ve been perusing Tom’s NYC places-to-get-hardware list. It’s good. Read it and memorize it or if someone wants to whip out some geo-ninja skills and map these all out, that would rule. – Link
One thing I would add to this list is Sid’s hardware in Downtown Brooklyn around the corner from Metrotech. It’s big and it’s near where I work so I can pick things up from there easy peasy.
Note: Where do you like to get stuff in the city and boroughs? Leave a note in the comments!