I saw the linked picture and wondered if there was a site that automatically allowed overlay of cities over other places? Preferably with statistics like population etc. http://i.imgur.com/Eqfme.jpg
Access to raw data via http://nominatim.openstreetmap.org/search?q=Orleans%20Parish...
but you have to convert it a little to geojson structure. There is already a bug ticket open to support format=geojson. Note the licence: the data is free including commercial use, but you have to attribute where you got it from.
There are a couple of other ways and tools to get that data.
It's really hard to find good data for these boundaries, especially for Orleans Parish in Louisiana. This is the only place I've found good data for Orleans (though, it's not free): http://www.maptechnica.com/us-county-boundary-map/county/Orl...