Where can you find electronics components in the NYC area?
Also see the list at [Local Resources / Parts].
The electronics shop at the rear of the 269 Canal Street mini-mall.
Barry Electronics was mentioned on the blog; they're a ham radio dealer with a storefront at 224 W. 35th St., between 7th and 8th Avenues, in Suite 408.
Argo, a junk store west of West Broadway on Canal. Boxes of awful electronic crap, cheap cables and broken stuff with a few parts and salvageable items.
In a pinch, Radio Shack stores have some components and tools, although the stock varies quite a bit. The store in Park Slope, Brooklyn at 7th Avenue and 5th Street and the store at Flatbush and State St. both have small cabinets of parts, while the one at Broadway and 17th Street near Union Square in Manhattan has a bit more stock on hand.
What about online?
If you're looking for a specific part, try the Octopart search engine. They cross reference a lot of distributors and link to datasheets. It's a great tool when you're staring at a PC board and wondering what a component does.
Another similar site is Component Search which searches 1000+ verified component distributors and provides datasheets and will help you find the lowest price.
 isn't as great of an interface, but finds things that Octopart doesn't.
Also, see our listing of online retailers at Mail Order Resources / Parts