I wrote up how to build a US Census Tract database earlier. However, we all know that data without a way of showing it on a map, is a little sad. So I wrote up the process I used to make it all available on a Google Map. The process involves the use of PostGIS, Mapnik, Node.js and just a smidge of magic. Its a longer post, so i lumped it in with my tutorials. You can go check it out here.