Ben, that interactive map that zooms in with all the counties in a state is pretty friggin nifty. Did you make that from scratch with a n ip-to-location data set, or use some kind of location API??
To get location I do a variety of things mostly based off of the IP address of a user. However, I've built up a lot of meta data around locations which I may release later on down the road. Happy to talk more if you want to email me.