Via Bean, here’s a fun little tool that gives you economic and demographic information for your zip code, and compares it to surrounding zip codes.
One huge caveat: this is based on 2000 census data. And things have changed a lot in the past 7 years. My neighborhood, for example, into which I moved just over 6 years ago, has gentrified quite a bit just since I’ve been here. So I’m pretty skeptical that the median income figures and the percentage of the households under the poverty line are the same. OTOH, there are still a ton of immigrants, many of them low-income, so I don’t know. Certainly, the figures make sense relative to, say, Park Slope (11215).