I'm hoping to write an expanded post about this, but for now: we're using the 2009-2013 American Community Survey (a product the Census Bureau puts out yearly, rather than the every-ten-years Census). You can download CSVs of the whole thing here: http://www2.census.gov/programs-surveys/acs/summary_file/201.... We took those and TIGER data (geospatial data specifying what areas each of the stats in the CSV correspond to), and put them into a Postgres db with PostGIS.
If you're not looking to show the whole US at a granular level like we are, you might be able to skip the FTP server approach a few ways. They recently released CitySDK (https://uscensusbureau.github.io/citysdk/), which seems like a nice way to get at Census data from the browser, though I haven't personally used it. There's also a set of APIs (https://www.census.gov/data/developers/data-sets.html), which might work depending on what specifically you're trying to do. A third way to get at it is to use American FactFinder (http://factfinder.census.gov/faces/nav/jsf/pages/index.xhtml), which lets you drill in and search for whatever fields and/or geographies you care about, and export them.
If you just want to browse around Census data, I also love Census Reporter (http://censusreporter.org).
If it's not harmful to any competitive advantages you have, it would be lovely if you could do a blog post of all the open data sources you know of (or, are there any directories that maintain up to date lists of open data sources?)
If you're not looking to show the whole US at a granular level like we are, you might be able to skip the FTP server approach a few ways. They recently released CitySDK (https://uscensusbureau.github.io/citysdk/), which seems like a nice way to get at Census data from the browser, though I haven't personally used it. There's also a set of APIs (https://www.census.gov/data/developers/data-sets.html), which might work depending on what specifically you're trying to do. A third way to get at it is to use American FactFinder (http://factfinder.census.gov/faces/nav/jsf/pages/index.xhtml), which lets you drill in and search for whatever fields and/or geographies you care about, and export them.
If you just want to browse around Census data, I also love Census Reporter (http://censusreporter.org).