What is the best way to read, represent and render map data?

Question

I am interested in writing a simplistic navigation application as a pet project. After searching around for free map-data I have settled on the US Census Bureau TIGER 2007 Line

Answer 1

Though you already decided to use the TIGER data, you might be interested in OSM (Open Street Map), beacuse OSM has a complete import of the TIGER data in it, enriched with user contributed data. If you stick to the TIGER format, your app will be useless to international users, with OSM you get TIGER and everything else at once.

OSM is an open project featuring a collaboratively edited free world map. You can get all this data as well structured XML, either query for a region, or download the whole world in a large file.

There are some map renderers for OSM available in various programming languages, most of them open source, but still there is much to be done.

There also is an OSM routing service avaliable. It has a web-interface and might also be queriable via a web service API. Again, it's not all finished. Users could definitely use a desktop or mobile routing application built on top of this.

Even if you don't decide to go with that project, you can get lots of inspiration from it. Just have a look at the project wiki and at the sources of the various software projects which are involved (you will find links to them inside the wiki).