Getting US census data for a combination of geographies (e.g. county + tract) and finding which of the over 50,000 fields you would like is kind of a pain, to put it mildly.

I built a tool to visualize all geography areas on a map and allow you to easily add them to a report.

A quick search allows you to quickly find the data properties you need.

Your report parameters are kept in the URL for sharable/bookmarkable state.

A cool implementation detail is that an in-browser database stores the 22,000 objects needed to render the geo shape files efficiently.

Give it a spin here