Verticle search and map mashups are a big part of Web 2.0, and  we generally expect maps to be useful. the obvious monetization is real estate, and sites like Zillow have been focusing in on that industry assiduously, providing users with lucrative data about price and valuation. There's even a user-generated component where visitors can improve the data by claiming their home and suggesting better valuations. There's been some controversy about the accuracy of this data, but the basic principle still holds: an interactive, two-dimensional way of getting a sense of a neighborhood.

Or a sense of its finances, rather. For those of us who might be equally interested in a neighborhood's  character, there are still more startups springing up. One such is the charmingly named Neighboroo, recently released in a very quiet Beta, which uses heatmaps (wherein a range of color gives you a sense of numerical scale) to display data about housing prices--and politics, air quality, crime, ethnicity, unemployment and other interesting demographic data.