Recently I’ve been doing lots of map-making with D3.js. Specifically Choropleths.
If you find youself trying to clean up location data, you need to introduce yourself to the boys and girls at SmartyStreets. Their webservice has been a huge time saver when having to clean up addresses, geotag them and obtain corresponding US county and FIPS codes.
Their tech support is awesome. Props to Jeffrey, their Street Genius!