http://leafletjs.com/

Here I demonstrate the use of the leaflet.js library - an awesome open source way for creating
interactive maps

for ref:
http://leafletjs.com/examples/quick-start.html

Using GeoJson

for ref:
http://leafletjs.com/examples/geojson.html
http://leafletjs.com/reference.html#geojson

Interactive Choropleth Map

for ref:
http://leafletjs.com/examples/choropleth.html
http://leafletjs.com/reference.html#icontrol
http://leafletjs.com/examples/choropleth-example.html

CA Zip codes Choropleth Map

for ref:
http://leafletjs.com/examples/choropleth.html
http://leafletjs.com/reference.html#icontrol
http://leafletjs.com/examples/choropleth-example.html