PolicyMap is a collection of real estate, civil, and financial systems built into a mapping and charting engine. It can locate superfund sites; show you crime stats; tell you about mortgage originations (including things like subprime mortgages to various demographic groups), and age and educational background. The data is at a variety of resolutions (some is per ZIP code, some by census tract) and timeliness.
In many data sets you zoom into deep detail on your information. You can also build charts, for data sets with information over time, and generate preconfigured "community reports" for particular regions or any areas you define. Needless to say, the one thing PolicyMap is not lacking is data. It's also free to use, if you are accessing public data. Some data sets, such as home sale statistics, require a paid membership, for $200 a month.
Unfortunately, despite all of the data and all the options to display it, a few useful views are missing. For example, while you can easily see the percentage of people per census tract within a certain age range (such as 18 to 34), there's no report that I found that can help you visualize average age. And here's a tip: Don't press the back button to try to undo a mapping step; it doesn't work as you expect and will just get you lost.